Messages of gratitude and support for President Joe Biden poured in following his stunning announcement Sunday that he is exiting the 2024 presidential race and endorsing Vice President Kamala Harris as the next Democratic nominee.

Pressure had mounted on Biden to pull out of the race since his disastrous performance at the CNN presidential debate last month, and on Sunday, he confirmed he would remain a one-term president.

British PM Keir Starmer said he respects the president’s decision and looks forward to working together for the remainder of his term.

“I know that, as he has done throughout his remarkable career, he will have made his decision based on what he believes is best for the American people,” Starmer wrote on X.

Canadian PM Trudeau thanked Biden for being a “true friend” to his country. “He’s a great man, and everything he does is guided by his love for his country,” he said on X.

Ukrainian President Volodymyr Zelensky thanked Biden for his “unwavering support” in his country’s war against Russia, which the US has backed with weapons, military aid and diplomatic support, despite backlash from Republicans.

“Many strong decisions have been made in recent years and they will be remembered as bold steps taken by President Biden in response to challenging times,” Zelensky said on X. “We will always be thankful for President Biden’s leadership.”

Meanwhile, Kremlin spokesman Dmitry Peskov said Moscow was “not too surprised” by Biden’s withdrawal. “In recent years, what has been happening in the United States has taught us not to be surprised by anything,” Peskov told reporters Monday.

Irish Taoiseach Simon Harris called Biden “a proud American with an Irish soul,” and thanked him for his “global leadership” and “friendship.”

Other leaders commended Biden for making what must have been a tough decision to drop out of the race.

“My friend Joe Biden has achieved a lot: for his country, for Europe, for the world,” German chancellor Olaf Scholz wrote on X. “His decision not to run again deserves respect.”

Republicans call for his resignation

Leading Democrats were quick to hail Biden's legacy after his historic decision to end his reelection bid, while Republicans instead demanded his resignation.

From former presidents to current lawmakers, Biden's party faithful rallied around him as he passed the torch to Vice President Kamala Harris, endorsing her to take on Donald Trump.

Harris herself praised Biden's "selfless and patriotic act," saying in a statement that his accomplishments are "unmatched in modern American history, surpassing the legacy of many Presidents who have served two terms in office."

Barack Obama, who picked then-senator Biden as his running mate in 2008, called him a "patriot of the highest order," but warned of "uncharted waters in the days ahead" -- and stopped short of endorsing Harris.

Former House speaker Nancy Pelosi, who still wields immense influence among Democratic lawmakers and had reportedly been pushing for Biden's exit, said in a statement that "his legacy of vision, values and leadership make him one of the most consequential Presidents in American history."

Republican leaders, including Trump, slammed Biden's presidency and called for the 81-year-old to resign.

"Crooked Joe Biden was not fit to run for President, and is certainly not fit to serve -- And never was! ... We will suffer greatly because of his presidency, but we will remedy the damage he has done very quickly. MAKE AMERICA GREAT AGAIN!" Trump, 78, posted on his Truth Social network.

Senator J.D. Vance, Trump's pick for running mate, said Biden "has been the worst President in my lifetime and Kamala Harris has been right there with him every step of the way."

House Speaker Mike Johnson meanwhile said that "if Joe Biden is not fit to run for president, he is not fit to serve as president."

"He must resign the office immediately," he said in a statement.