Joining other top Republican officials, Senate Minority Leader Mitch McConnell, R-Ky., endorsed former Massachusetts Governor Mitt Romney for president on Tuesday, saying the GOP is united behind the presumptive nominee.Earlier this month, McConnell avoided giving Romney the nod because the Kentucky primary was approaching. But with former Pennsylvania Senator Rick Santorum dropping out of the race—and basement candidates Newt Gingrich and Ron Paul barely campaigning—the pathway for Romney to gain the nomination against President Obama is much clearer.McConnell says polling shows the race will be very competitive and he is looking forward to the fall campaign."I support Governor Romney for President of the United States and he is going to be the nominee," he told reporters. "If you've noticed, the party is in the process of unifying behind him. And I think it's going to be an incredibly close, hard fought race."The first Gallup poll of the general election shows Romney ahead of President Obama by two percentage points, which is within the margin of error.