Following Mitt Romney's double-digit win in the Illinois Republican presidential primary, former Florida Gov. Jeb Bush (R) is calling "for Republicans to unite behind Governor Romney."

In a statement released on Wednesday morning, Bush said he was throwing his support behind the former Massachusetts governor.

"I am endorsing Mitt Romney for our Party’s nomination," Bush said. "We face huge challenges, and we need a leader who understands the economy, recognizes more government regulation is not the answer, believes in entrepreneurial capitalism and works to ensure that all Americans have the opportunity to succeed."

NBC senior political reporter Mark Murray observed that Bush's backing was "a cherry on top of his victory in Illinois."

"I was actually struck by Jeb Bush's statement where he said that it is time for the Republican Party to unite around Mitt Romney," Murray explained. "As we've seen, polls have shown that this Republican primary season has taken a toll on its candidates including Romney. Romney only has about $7 million in the bank. So, you are seeing people saying, 'Look, it's time to end this race. Let's go to the general election.'"

As expected, surrogates for former Pennsylvania Sen. Rick Santorum and former House Speaker Newt Gingrich immediately downplayed the endorsement simply as the GOP establishment trying to select their preferred nominee.

"We're doing this without the big-named endorsements, without the establishment endorsements," Santorum press secretary Alice Stewart told MSNBC's Thomas Roberts. "Rick is out there to get the endorsement of the American people and he is doing very well doing that."

Gingrich's spokesman reportedly called Bush's support "a completion of the Establishment tri-fecta," referring to other endorsements from former President George H.W. Bush and former Republican presidential nominee Bob Dole.

Watch this video from MSNBC, uploaded March 21, 2012.