Jeb Bush has finally decided to firebomb Donald Trump

The GOP presidential contenders are now taking a different approach to front-runner Donald Trump.

The billionaire mogul has been leading his party rivals in the polls for weeks and is now beginning to show up in the rear-view mirror of current Democratic front-runner, Hillary Clinton.

Trump's rivals are starting to openly question the legitimacy of Trump's status as a Republican.

During a town hall meeting Wednesday in New Hampshire, Jeb Bush took issue with Trump's credibility.

"Mr. Trump doesn't have a Conservative record. He was a Democrat longer in the last decade than he was a Republican," said Bush.

Bush went on to assert that Trump "has given more money to Democrats than he's given to Republicans."

The former Florida governor outlined Trump's past support of tax hikes on people who have more than $10 million in assets, and Trump's support of a single-payer health care system.

"Not a very Conservative point of view, " Bush said. 

He also criticized Trump's "vitriolic" rhetoric on immigration reform. 

You can see Jeb Bush's full commentary on Trump here:

Rand Paul is also attempting to pick apart the veneer of Trump's conservative crusade, implying Trump is a "closet Democrat."

Paul, according to The Guardian, is running ads that feature quotes attribited to Trump from 1999, in which Trump declared, "In many cases, I probably identify more as a Democrat," and "it just seems that the economy does better under the Democrats than the Republicans." 

You can see the Rand Paul ad here: