Bush backers flock to Rubio
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Lawmakers are flocking to support Marco RubioMarco Antonio RubioColbert: Students taking action on gun violence 'give me hope' Lawmakers feel pressure on guns Florida lawmaker's aide fired after claiming shooting survivors were 'actors' MORE's White House campaign after former Florida Gov. Jeb Bush dropped out of the GOP race on Saturday.

A slew of Republicans in Congress who previously backed Bush are moving to support Rubio as he battles GOP rivals Donald TrumpDonald John TrumpAccuser says Trump should be afraid of the truth Woman behind pro-Trump Facebook page denies being influenced by Russians Shulkin says he has White House approval to root out 'subversion' at VA MORE, Sen. Ted CruzRafael (Ted) Edward CruzOvernight Health Care: Trump eases rules on insurance outside ObamaCare | HHS office on religious rights gets 300 complaints in a month | GOP chair eyes opioid bill vote by Memorial Day HHS official put on leave amid probe into social media posts Trump, Pence to address CPAC this week MORE (Texas) and Ohio Gov. John Kasich.

Rubio's campaign announced ahead of Tuesday's caucus in Nevada that Sen. Dean HellerDean Arthur HellerThe siren of Baton Rouge Big Republican missteps needed for Democrats to win in November What to watch for in the Senate immigration votes MORE (Nev.) and Rep. Mark AmodeiMark Eugene AmodeiInterior agency delayed tribal casino approval after competitor’s lobbying: report DACA advocates see efforts gaining steam in the House Overnight Finance: House passes .2T funding package for 2018 | FTC launches Equifax probe | Mnuchin defends honeymoon jet request | MORE (Nev.) would be backing his campaign.

Florida Reps. Carlos Curbelo, Mario Díaz-Balart, Ileana Ros-Lehtinen, Gus Bilirakis and Jeff Miller, all former Bush backers as well, announced their support for Rubio on Monday afternoon.

"Marco is a super outstanding member of the Senate but he's had a great deal of experience—he was speaker of the House down there in Florida," he told reporters, adding that he's "honest, energetic and trustworthy." 

Rubio is hoping to shore up support among more of Bush’s supporters, who are also eyeing Kasich as a potential alternative to Trump, the clear front-runner in the GOP race.

“As much as I love John Kasich, you know, Rubio is probably a better candidate. And he’s young,” former GOP nominee Bob Dole told ABC News on Monday in announcing his support of Rubio.

"He wants to grow the party as opposed to [Ted] Cruz. I don’t know what he wants to grow," Dole added.

Rubio narrowly edged Cruz for second place in South Carolina, marking his comeback after a disappointing fifth place finish in New Hampshire earlier this month.

Rubio’s backers have characterized the Florida senator as a unifying force in the GOP race as lawmakers and donors scramble to encircle an alternative to Trump and Cruz.

“America needs a president who will take on the status quo, establishment and entrenched interests that are standing in the way of a better future for our people, and Marco will be that kind of president,” Miller said in a statement Monday shared with The Hill.

Miller, the chairman of the House Veterans Affairs Committee, praised Rubio’s work in the Florida legislature, saying, “Marco has stood with me in fighting for our veterans and holding the VA accountable for the unforgivable scandals and abuses we’ve seen in recent years.”

The growing number of endorsements for Rubio also helps gin up attention for the candidate as he spars for the spotlight with Cruz and Trump, but it's unclear how much they will affect the race in a year where candidates who have positioned themselves as political outsiders have held an edge.

Republicans acknowledge that Rubio and others face a difficult path to the nomination in the face of Trump, who remains a dominant force with wins in New Hampshire and South Carolina. 

House Majority Leader Kevin McCarthy (R-Calif.) said early Monday that while he sees a two-person race between Trump and Rubio, there's more than a "50 percent chance" that Trump will be the nominee.