BALTIMORE (WJZ/AP) — Political leaders are praising Barbara Mikulski and her legacy.

President Barack Obama says retiring Sen. Barbara Mikulski is an institution in the Senate whose leadership is inspiration for millions of women around the world.

In a statement, he said, “Senator Mikulski is more than just a legendary senator for the people of Maryland, she’s an institution in the United States Senate. Barbara’s service to the people of Maryland spans decades, but her legacy will span generations. Barbara is the longest serving woman in Congress, and her leadership serves as an inspiration to millions of women and girls across the globe to stand up and lead.

“As the Chairwoman and now Vice Chairwoman of the Senate’s Appropriations Committee, Barbara has always known that our budgets should reflect our deepest held values. In that spirit, Barbara has wielded her gavel and used her booming voice to advocate on behalf of paycheck fairness, childcare, health care, education, women’s rights and countless issues that have contributed to the strength of America’s families. Thanks to her leadership, more women excel in their careers, more children have access to quality education, more families have health insurance and more people are treated fairly under the law. I look forward to working with Senator Mikulski over the course of the next two years, and Michelle and I extend our warmest wishes to Barbara in her next endeavors.”

Vice President Joe Biden said, “It has been the honor of a lifetime to work alongside my friend Barbara Mikulski. I will always be proud to be able to tell my four granddaughters that I served with a Senator who changed the way we think about each other in this country.

It was her leadership that brought the nation’s attention to the need for shelters for victims of domestic violence, helping countless women escape the worst prison on earth – the four walls of their own home. She helped me pass the Violence Against Women Act in 1994, and she successfully fought for every reauthorization since.

There’s a lot of talk about what the women of America owe Barbara Milkulski, but the truth of the matter is the men of America owe her even more. Because she freed men of the stereotypical notions that they were raised to believe.

When they saw the accomplishments of their daughters, when they saw their wives and their mothers take on new roles, when they saw the people they loved the most take on responsibilities that they had not seen before in their lives, it liberated them too.

I am sorry to see her go, but there are still two years left. And two years of Barbara Mikulski is like six years of any other senator. Jill and I wish her all the best.”

Sen. Barbara Mikulski, the longest serving woman in the history of Congress, announced Monday that she will not run for-re-election.

“`Do I spend my time raising money, or do I spend my time raising hell?”‘ the 78-year-old old Maryland Democrat, now in her fifth term, said she asked herself when deliberating whether to seek a sixth term next year.

WATCH: Sen. Barbara Mikulski Announces She Will Not Seek Reelection

“I don’t want to spend my time campaigning for me. I want to campaign for the people,” she said at a news conference in the Fells Point neighborhood of Baltimore. “Do I spend my time promising what I would do — or do it now and do it the way I like to?”

Mikulski, a tough, no-nonsense lawmaker who rose to the leadership of the powerful Appropriations Committee, became the longest-serving woman in the history of Congress in 2012. She was first elected to the House of Representatives in 1976 and has served in the Senate since 1987.

She said that when her term has ended, “I will know that I will have given it my best shot.”

Her retirement is certain to set off a race among potential candidates to succeed her, including Democratic Reps. Chris Van Hollen and Donna Edwards, and former Govs. Martin O’Malley, who is considering a bid for the Democratic presidential nomination, and Republican Bob Ehrlich.

She becomes the second Senate Democratic woman to announce her retirement this year, following Barbara Boxer of California.

In a 2014 interview, Mikulski said her approach as chair of the Appropriations panel was “to focus with civility and courtesy. Old school values. Don’t do surprises or stunts and negotiate directly and not through the press.” In her state, she has been fiercely protective of the environment, especially Chesapeake Bay issues.

Senate Republican Leader Mitch McConnell described Mikulski at the time as forceful and results-oriented. “I think she’s terrific,” he said.

Mikulski had been seen as more engaging and approachable than her predecessors as appropriations chairman, the late Sens. Robert C. Byrd, D-W.Va., and Daniel Inouye, D-Hawaii. She had spent decades honing relationships with members of both parties, learning their needs and end goals.

After a short tenure as chairman, she now is the top Democrat on the panel after Republicans captured control of the Senate in last November’s elections.

“She knows that if you know somebody and what they want, you can help them be successful. And when you help people be successful, Republicans or Democrats, that’s how you move bills,” said Democratic Sen. Patty Murray of Washington, a Mikulski protege.

Mikulski has also been an active advocate of equal pay for women. The Maryland senator sponsored legislation last year aimed at tightening a 1963 law that made it illegal to pay women less than men for comparable jobs because of their gender. But Senate Republicans blocked the bill in an April 2014 floor showdown.

“When I hear all these phony reasons, some are mean and some are meaningless, I do get emotional,” Mikulski said of arguments against the legislation. “I get angry. I get outraged. I get volcanic.”

Mikulski played off former CIA Director Michael Hayden’s recent comment that Senate Intelligence Committee Chairwoman Dianne Feinstein, D-Calif., was motivated by “emotional feeling” when she sought an investigation of the spy agency’s harsh treatment of terrorism suspects.

Congressman Dutch Ruppersberger issued a statement Monday. “It is fitting that Senator Mikulski announce her retirement as we begin Women’s History Month – she has truly made history both by her extraordinary longevity and her tenacious leadership. Not only is she the longest-serving woman in the Senate and the first Democratic woman elected to the chamber in her own right, she is Maryland’s Number One advocate.

“Two things I know about Senator Mikulski have always impressed me in her public service. The first relates to her father’s corner store on South Eden Street in Baltimore. When he opened his doors each day, he would say, ‘How may I help you?’ Senator Mikulski has lived by that mantra every day of her life for the people of the State of Maryland. She has worked tirelessly for critical resources to improve our roads, schools and police, to create jobs and create opportunities.

“The other thing that impresses me is a favorite saying of hers: ‘It’s not about the building.’ Senator Mikulski has never cared about the bricks and mortar. She cares about the people that work inside the building, what they do, how they help the citizens and how she can help them help others.

“I am very proud to call Senator Mikulski my friend, starting from our days back in local government. I thank her for her service to the people of Maryland and wish her all the best in her retirement. Her successor has big shoes to fill.”

Mayor Stephanie Rawlings-Blake issued a statement saying, “A pioneer, a fierce competitor, and a Baltimorean to her very core, Senator Mikulski has proudly served Maryland and the nation as an outstanding senator and as a mentor to women like myself. Senator Mikulski repeatedly shattered glass ceilings and paved the way for new generations of women leaders. Thanks to her decades of service and her readiness to ‘raise hell’ for her constituents, today we all enjoy a stronger, more diverse country. On behalf of the City of Baltimore, I want to thank her for all she has done for us, and I wish my good friend and mentor the very best in retirement.”

Congresswoman Donna F. Edwards released a statement after Mikulski announced her retirement: “Senator Barbara Mikulski is a groundbreaking champion for the state of Maryland, an inspiration to women all across our country, and my mentor in the Congress. As the longest serving woman in the history of the Congress and the first duly elected on her own, she is one of Maryland’s greatest leaders, and her legacy will echo for generations to come. I value our tremendous partnership on securing scientific funding critical to our state, creating an emergency preparedness initiative for our region centered at Prince George’s County Hospital, and protecting women’s rights and health in the landmark Affordable Care Act. I join all Marylanders and countless others around the country in thanking her for 30 years of service in the Senate and wish her all the best as she begins a new chapter in her life.”

In a statement, DSCC Chair Senator Jon Tester said, “Barbara Mikulski is as well-respected of a legislator as anyone I’ve served with in the U.S. Senate and it has been my privilege to work with her. Her unyielding commitment to the people of Maryland is matched only by the sheer number of lives she’s inspired over her long career. Barbara is a force of nature on the Senate floor and she will be missed both by her colleagues and her constituents. I am confident that in November 2016 we will elect a new Democratic senator who will fight for Maryland every day and make Barbara Mikulski proud.”

Congressman Elijah Cummings also released a statement about Mikulski’s decision:

Senator Barbara Mikulski is a giant in public service whose accomplishments speak for themselves. As the longest serving woman in the history of the Congress, she has set the standard for excellence that others may match but will never exceed.

Throughout her career, Senator Mikulski has been a voice for the voiceless and has doggedly fought to ensure that all people – regardless of their backgrounds or circumstances – can have access to all the American Dream has to offer.

I am deeply grateful for the leadership she has provided to our state’s delegation and for her mentorship to me throughout the years.

Senator Mikulski’s presence will be sorely missed on Capitol Hill, but her legacy will most assuredly live on in the lives of everyone she has fought for over the course of her decades of service to our state and our nation.

I came to the Senate with Barbara Mikulski and I have had no better friend in my time here than Barbara Mikulski.

— Senator Harry Reid (@SenatorReid) March 2, 2015

“Senator Barbara Mikulski’s career has been devoted to serving others. As a social worker in Baltimore, she fought for at-risk children and to protect seniors from abuse. On the Baltimore City Council, and during her nearly 40 years of service in the United States Congress, she has fought for struggling Americans, demanded women be paid equal pay for equal work and led in the fight to protect the promise of Social Security and Medicare for seniors,” Reid added.

He continues: “Barbara Mikulski is a trailblazer – the first woman elected to the United States Senate from Maryland and the first woman to become Chair of the Senate Appropriations Committee. And as Dean of the women of the Senate, Barbara has been a mentor and friend to Senators on both sides of the aisle. Through her work, she has helped a generation of women leaders rise in the Senate.

Barbara Mikulski’s voice has boomed through the halls of the Congress and has helped guide our nation through some of our country’s most trying times. I will always remember her strength on September 11th and the days that followed. As Members of Congress returned to the Capitol and met on the steps that terrible day, Senator Mikulski’s voice rose above us all as she said, “We’ll sing ‘God Bless America.’” And we did. It was a poignant moment that I will never forget.

I thank Barbara Mikulski for her many years of hard work and friendship. I look forward to continuing our work together as Barbara finishes out her term.”

(Copyright 2015 by The Associated Press. All Rights Reserved.)