Planned Parenthood and other pro-abortion rights groups are cheering on Vice President Kamala Harris, saying she will "fight like hell" for abortion rights. Harris has led the charge under Biden's presidency with abortion rights, a major issue in the 2024 election.

"As we have navigated this public health crisis, Vice President Harris has kept the needs and experiences of patients and providers front and center. She’s the first Vice President to visit a Planned Parenthood health center -- and we know that she will continue to fight like hell to rebuild a fundamental right that was stripped away," Planned Parenthood said in a statement Sunday.

"President Biden and Vice President Harris’ record when it comes to protecting our reproductive freedoms and abortion access is unquestionable -- these last two years, they have been the strongest, steadiest voice in the post-Dobbs storm," Planned Parenthood said.

President Joe Biden told his senior team that he had changed his mind about staying in the race one minute before going public, a source told ABC News.

Biden told his team at 1:45 pm on Sunday, and posted his announcement to the public at 1:46 pm, the source said.

As recently as Saturday night, according to the source, Biden’s message had still been “full speed ahead.”

-ABC News' Selina Wang

Sen. Amy Klobuchar, D-Minn., told ABC News she is backing Vice President Kamala Harris for president in the 2024 election.

"I worked with her in the Senate for years and we became closer friends even when we ran against each other," Klobuchar said.

Klobuchar said President Joe Biden chose "the honorable path" by dropping out.

"President Biden has served with integrity and delivered results that will strengthen our country for generations to come. He passed historic legislation investing in our infrastructure, manufacturing and lowering the cost of prescription drugs. I am deeply grateful for his service, dedication, and commitment to our country and our democracy," Klobuchar said.

-ABC News' Selina Wang

Marianne Williamson is throwing her hat back in the 2024 presidential election ring after President Joe Biden exited the race Sunday.

"The nomination of a new Democratic candidate must be opened to a genuinely democratic process at an open convention," Williamson told ABC News in a statement.

"No one should simply be anointed to the position of nominee; all candidates must be heard and their agendas explored," Williamson said, seemingly referencing Biden's endorsement of Vice President Kamala Harris.

"Our party’s basic first principle is democracy," Williamson continued, adding, "We cannot save our democracy without practicing it ourselves."

"I look forward to taking my message to the American people, and convincing Democratic delegates, that I am the best candidate to take us to victory in November," Williamson said.