President Obama today offered personal congratulations to GOP rival Mitt Romney for formally clinching the Republican Party presidential nomination in Tuesday's primary.

Obama spoke with Romney by phone around 11:30 am ET, aides on both sides said. The president placed the call from the White House, reaching Romney in Las Vegas, where he was preparing to depart to California for a day of fundraisers.

"The president called Governor Romney to congratulate him on securing the Republican nomination," Obama campaign spokesman Ben LaBolt said in a statement. "President Obama said that he looked forward to an important and healthy debate about America's future, and wished Governor Romney and his family well throughout the upcoming campaign."

White House spokesman Jay Carney later described the conversation as "very collegial and friendly," but added " not, of course, particularly long."

A Romney campaign aide said in a readout that the exchange as "brief and cordial" and that the governor "thanked the president for his congratulations and wished him and his family well."

The call is the first time the two men have spoken since the start of the GOP primary race and one of the few times they have ever connected in person.

The president has publicly noted that he does not know Romney well, unlike his 2008 rival - Sen. John McCain - who was a colleague in the Senate.

"I've met him, but we're not friends," Obama said of Romney in an appearance on "Late Night with Jimmy Fallon" last month. "His wife is lovely," he added of Ann Romney.

At campaign rallies, Obama also heaps personal praise on Romney before criticizing his record in business and as governor. "Governor Romney is a patriotic American.  He's raised a wonderful family.  He should be proud of the great personal success he's had as a CEO of a large financial firm," Obama said last week at a rally in Des Moines, Iowa

For his part, Romney often refers to Obama as a "nice guy" on the trail, but quickly follows up with "he just doesn't know how to run the economy."

"Obviously, we have a very different view. The president I'm sure wants another four years. But the first years didn't go so well," Romney told ABC News' Diane Sawyer in an interview last month.

"I don't connect with President Obama because he doesn't understand the economy. He doesn't understand what it takes to get jobs for the American people. I do," Romney said.

Ann Romney, in the same interview, said of the first lady, "I got to know Michelle, she's a lovely person. I've never met Barack Obama, but I believe it's Mitt's time."