Awaiting Donald Trump to endorse Mitt Romney, MSNBC’s Martin Bashir asked what value this would have the former governor of Massachusetts. Most would say it’s negligible. But I am convinced that it is part of Romney’s ongoing effort to convince the conservative lifeblood of the Republican primary electorate that he is one of them, that he can be trusted. Without them, he can’t win the nomination.

How else to explain his embrace last December of Christine O’Donnell? The Tea Party darling and Republican candidate for Senate from Delaware ran a disastrous campaign. She was obliterated at the polls in 2010 by 17 points. But when the woman who had to declare “I am not a witch” endorsed him, Romney issued an implausible statement that called O’Donnell “a leader in the conservative movement for many years” and added, “I am pleased to have her on my team.”

Now he has Trump, who rode the the long-debunked birther conspiracy theory to the top of the polls of possible GOP contenders nearly a year ago, and who has a following within the Republican Party because of his tough talk against President Obama, particularly with regard to China. Ultimately, this could all be window dressing. But NBC News political director Chuck Todd pointed to two Florida primary exit poll numbers that show why Romney’s task of reassuring the conservative base is vital if he wants to be the Republican nominee.

41 percent said Romney’s positions on the issues are “not conservative enough”

38 percent said they “would like to see someone else” get in the race

The conservative base is restive and unsatisfied. And Romney doesn’t have its support locked up. He’s casting about for validation and acceptance, which helps to explain why the man who chose stealth for his September meeting with The Donald in New York opted for the bright lights and cameras today in Las Vegas.