LAS VEGAS, Nev. – After a day in which his message was overshadowed by talk of Donald Trump and birtherism, Mitt Romney's appearance at a fundraiser at Trump's hotel showed the fine line he walks between embracing the brash billionaire and keeping him at a safe distance.

Tuesday night's event, which was expected to raise upwards of $2 million for Romney’s campaign, followed a day in which Trump doubled down on his claims that President Obama was not born in the United States and was instead born in Kenya.

"A lot of people do not think it was an authentic certificate," Trump said of Obama's Hawaii birth certificate in an interview on CNN just hours before he hosted Romney's fundraiser. Democrats slammed Trump's position throughout the day, believing it can win them voters who find such talk repugnant.

Romney did not address Trump’s new comments on Tuesday, but told reporters earlier that he doesn’t agree with all of his supporters, including Trump. "And my guess is they don't all agree with everything I believe in," Romney said. "But I need to get 50.1 percent or more. And I'm appreciative to have the help of a lot of good people."

Neither Romney nor Trump referenced the controversy at the Tuesday evening fundraiser, where Trump introduced the now-official Republican nominee by telling the crowd that Romney would be “a great, great president.” Romney responded by thanking his host for “twisting the arms that it takes to bring a fundraiser together” – a nod to the connections that Trump provides.

But the former Massachusetts governor made a point of highlighting a key difference between his worldview and that of Trump’s when he told a story that shed light on his viewpoint of the United States' role when it comes to war.

Trump, speaking about the decline he sees in the country’s military philosophy, said that America was getting “nothing” from its recent wars. “You know in the old days, you won a war, ‘To the victor belong the spoils,’” Trump said during his introduction of Romney. “With us, we win a war, what do we do? We leave Iraq, what did we get out of it? They're having a field day with the second largest oil reserves in the world; we get nothing. It's just a very, very sad situation.”

In contrast, Romney chose to tell a story about a time he was with former Israeli Prime Minister Shimon Peres at the height of the Iraq war when Peres was asked what he thought about America’s participation in the conflict. Romney said he expected the liberal former head of state to be critical, but instead he offered "context."

“He said ‘America is unique in history of earth.’” Romney told the audience. “He said ‘In the history of the earth, whenever there’s been conflict, the nation that wins takes land from the nation that loses, because land has always been the source of value on the planet. (Peres) said, ‘One nation in history has laid down hundreds and thousands of the lives of its sons and daughters and taken no land – no land from Germany, no land from Japan.”

He continued, “This is a great nation. A nation of people who will sacrifice for things bigger than themselves.”

Romney was also joined at the Vegas fundraiser by former Republican competitor Newt Gingrich, who told reporters before the event that he thought Romney was doing a good job of focusing on the economy, rather than getting pulled into a discussion about Obama’s birthplace.

“Governor Romney's not distracted,” Gingrich said. “The Republican party's not distracted. We believe that this is an American-born, job killing president. Other people may believe that he was born somewhere else and still kills jobs, but that's an argument over background.”

The former House speaker said it would be “hopeless” to try to tell Trump what he should or should not speak about. Asked if the billionaire businessman was a “loose cannon,” Gingrich laughed. “No, he's a loose entrepreneur,” he said. “He has made his fame by being who he is.”