Updated 5:31 p.m. ET

New polls show Rick Santorum poised for a "big day" in today's GOP presidential contests in Colorado, Minnesota and Missouri.

Bragging rights are the only thing at stake in the three states, which won't award delegates to the Republican National Convention in Tampa until district and state conventions or caucuses later this year.

STORY: Santorum aims for Romney

BLOG: Gingrich plays down his chances

The surveys by Democratic-leaning Public Policy Polling show Santorum possibly headed for a victory tonight in Missouri, where he leads Mitt Romney, 45% to 32%. The former Pennsylvania senator is also leading Romney in Minnesota, 33% to 24%.

Romney's best showing in the PPP surveys is in Colorado, where he has a 10-point lead over Santorum, 37% to 27%. Newt Gingrich is at 21% in Colorado, followed by Ron Paul at 13%.

"Rick Santorum has the potential to firmly establish himself as the conservative alternative to Mitt Romney today," said Dean Debnam, president of Public Policy Polling. "If he can pick up two wins and a second, it will raise significant questions about both Romney's inevitability and about the purpose for Newt Gingrich's continued presence in the race."

Former Minnesota governor Tim Pawlenty, a leading surrogate for Romney, told CNN today that Santorum's record on things such as congressional earmarks shows he "is not the perfect conservative he holds himself out to be."

"His rhetoric and record don't match up," said Pawlenty, who abandoned his own presidential bid in August and threw his support to Romney shortly after.

Santorum, meanwhile, has pointed to Romney's role in signing a health care law in Massachusetts that contains an individual mandate for insurance as evidence that his rival is "dead wrong" on one of the key issues in the campaign.

As for the attacks from Pawlenty and the Romney campaign, Santorum played down those campaign tactics in a recent CNN interview. "Governor Romney ... simply goes out and attacks and destroys," Santorum said.

A note about today's contests: Colorado and Minnesota are non-binding caucuses, while Missouri is hosting a primary that the St. Louis Post-Dispatch is calling "officially meaningless" for Republicans.

Polls close at 8 p.m. ET in Minnesota and Missouri, and 9 p.m. ET in Colorado.

Gingrich did not qualify for the Missouri primary, but is on the ballot in the other states.