WASHINGTON -- Senate Minority Leader Mitch McConnell (R-Ky.) isn't ready to endorse Mitt Romney as his party's presidential nominee, but he said the GOP primary has run its course and it's time for Republicans to start rallying behind their "almost certain nominee."

"It's pretty obvious this nomination is essentially over," McConnell said in a Thursday night interview on CNBC's “The Kudlow Report."

"I think we'd be a lot better off to begin to rally behind the almost certain nominee and begin to take the case against President Obama to the American people," he said. "I think more and more members are going to be embracing our almost certain nominee, and I think this matter's going to be wrapped up in a matter of weeks."

Still, McConnell stopped short when asked if he plans to endorse Romney.

"My view, so far, is that the Republican primary voters out around the country didn't need any particular advice from myself."

Romney has picked up several key endorsements in recent days, including former President George H.W. Bush, former Florida Gov. Jeb Bush and Sen. Marco Rubio (R-Fla.). Romney is also well ahead of his challengers with his delegate count. He currently has 568 delegates, compared to former Sen. Rick Santorum's 273, former House Speaker Newt Gingrich's 135 and Texas Rep. Ron Paul's 50. It takes 1,144 to win the nomination.