(Bloomberg News) Mitt Romney will join billionaire Donald Trump tonight in Las Vegas for a fundraiser five days after the real estate developer and reality television star sought to re-ignite debate about President Barack Obama's birthplace.

The appearance with Trump brings with it some political risk for the presumptive Republican presidential nominee and former Massachusetts governor.

Aside from the funds raised for his campaign, "there's no real advantage for Romney to appear with Trump," said Tobe Berkovitz, a communications professor and longtime Romney watcher at Boston University. "Anything Trump does is to benefit Trump. At this point, it's not like Romney needs publicity."

The fundraiser comes the week after Trump repeated his longstanding questions about whether Obama was born in the U.S.

"He didn't know he was running for president, so he told the truth," Trump said in a May 24 interview with the Daily Beast website, referencing a literary agency that once worked with Obama and included false information in a biography that he was born in Kenya. A former employee has said she made the error.

Obama released his long-form birth certificate in April 2011 and it showed his birthplace to be Honolulu, Hawaii.

"Donald Trump has become the birther-in-chief," Obama re-election spokesman Ben LaBolt said, a reference to those who insist Obama was not born in the U.S. "This once again raises questions about whether Mitt Romney will stand up to the extreme elements of his party or embrace them."

Securing Nomination

The Trump fundraiser will happen on an evening when Romney is poised to win enough additional delegates in the Texas primary to secure his party's nomination.

Trump's comments illustrate the risks associated with celebrity endorsers who have the potential to throw a campaign off message. Romney's campaign has sought to downplay Trump's remarks, while trying not to anger someone who can be helpful with fundraising.