Former Sen. Bob Dole, former Minnesota Gov. Tim Pawlenty and Arkansas Gov. Asa Hutchinson, along with three senators and a coterie of members of the House all endorsed Rubio just two days after former Florida Gov. Jeb Bush ended his bid for president, after a poor showing in South Carolina.
While Bush had struggled in the race and failed to keep up with Rubio's poll numbers, he had a strong hold on a number of party elders and endorsers. Others stayed on the sidelines so as not to pick between the two Floridians. With Bush out of the way, many were quick to back Rubio.
"Now that my good friend Jeb Bush is no longer running, I'm supporting Rubio," Dole told
ABC's "Political Powerhouse" podcast on Monday.
"I think it comes down to this -- he's strong, he's also informed, he's conservative, and he's electable, and he can unite the party, and you can't ask for much more than that," Pawlenty told CNN's Alisyn Camerota on "New Day."
"I think he's got the total package, and I think he's going to bring forward the strongest voice, the strongest image, and really the most thoughtful and informed strong view about how to move this country forward from a conservative perspective," he said.
Rubio also picked up the support of three Senate colleagues on Monday: former Bush-backer and Utah Sen. Orrin Hatch, Arizona Sen. Jeff Flake and North Carolina Sen. Thom Tillis.
Flake said his Senate colleague has the "toughness necessary to bring reform to Washington."
"In an election where serious solutions are seriously lacking, Marco Rubio has proven that he can inspire more than just anger in Americans who are looking for an alternative to the status quo," said Flake in a statement.
Hatch told CNN's Manu Raju that he called Rubio this morning to tell his Florida colleague he'd back his campaign. He also said Ohio Gov. John Kasich should get out of the race so Rubio could challenge front-runner Donald Trump.
"I think we're all worried about Trump. I like him too. I don't dislike the man, I just don't think he's ready to be president of the United States," Hatch said.
Hutchinson also backed Rubio nearly a week before his state's March 1 primary, after backing former 2016 candidate Mike Huckabee.
"The more I've watched this election unfold, the more I've come to see that Marco Rubio is the only candidate who can unite our nation the way Ronald Reagan once did," Hutchinson said in a statement.
Rubio also rolled out endorsements of Nevada lawmakers on the eve of the GOP caucuses there and from the South Florida congressional delegation, which had previously backed Bush.
Florida Reps. leana Ros-Lehtinen, Mario Diaz-Balart, Carlos Curbelo, Gus Bilirakis and Jeff Miller and Nevada Reps. Mark Amodei and Cresent Hardy announced their support late Sunday into Monday. Nevada Sen. Dean Heller also switched his support from Bush to Rubio on Sunday.
Rubio is aiming to turn the momentum into a financial advantage. The campaign of New Jersey Gov. Chris Christie, who left the GOP race after a poor showing in the New Hampshire primary, has sold its fund raising list to Rubio's campaign.
"Conservatives want an optimistic nominee with a vision for the 21st Century," Rubio said in a fundraising email pitch the day after the New Hampshire primary, "They want someone who can speak to all Americans, of all walks of life. They want a candidate who can beat Hillary Clinton. I'm going to be that candidate."
Still, former Minnesota Gov. Pawlenty dismissed the suggestion that Rubio represented the preferred candidate of the establishment, saying, "I think that's a misreading, because Marco Rubio came of age in the tea party. He's a bona fide movement conservative. And to say that he's 'establishment' or somehow not conservative, I just don't think is accurate. He's bold, he's next generation, and he's reform-minded, change-oriented."
Pawlenty also argued that Rubio is a better candidate than frontrunner Donald Trump.
"I think what people want in Donald Trump is strength, and in Marco Rubio you get that same strength, but it's an informed strength. And I think that's really important, particularly when you get to issues like national security and defense issues and foreign affairs," he said.
Pawlenty dropped out of the race in August 2011 and eventually endorsed Mitt Romney's 2012 presidential bid.