LOVELAND, CO - Rick Santorum is apparently throwing in the towel on the GOP's chances to take back the White House - unless he becomes the Party's nominee.

During a rally in Loveland, CO, the former senator blasted rivals Mitt Romney and Newt Gingrich with attacks he has been making for weeks.

Then, he went a step further.

"We are not going to win this election if either of these two guys is nominated," Santorum declared. "Let me assure you. We will not win."

Santorum claims neither candidate can compete with President Obama, saying both are simply too flawed and will be "destroyed" and "picked apart" by the Democratic incumbent.

Flawed or not, Republican voters seem to be rallying behind Mitt Romney, who pulled off yet another decisive victory Saturday in the Nevada caucuses.

Santorum however insists the real test is yet to come.

"Romney, Paul, and even Gingrich spent almost a million dollars each in Nevada; we spent a few pennies," Santorum told Fox News.

"On Tuesday I think we are going to do well in Missouri," he added. "It's going to be interesting because it's a head-to-head between Governor Romney and myself. Speaker Gingrich is not on the ballot. We will see the idea that one conservative can go up against Mitt Romney head-to-head and win."