GRAND JUNCTION – Health care and the partial government shutdown underscored the first debate between U.S. Sen. Mark Udall and Republican challenger U.S. Rep. Cory Gardner, who are deadlocked in a pivotal Colorado contest that could determine control of the U.S. Senate.

Gardner repeatedly tied Udall to the policies of President Barack Obama, frequently naming Udall and Obama in the same sentence, as well as referring to Udall’s support for the nation’s new health-care law and his vote for the 2008 stimulus plan.

“Barack Obama and Mark Udall have put tremendous pressure on this country,” Gardner said.

Udall countered by criticizing Gardner for siding with Republicans during the partial government shutdown in the aftermath of devastating floods in Colorado last year.

“You hurt the people of Colorado. You hurt the recovery,” Udall said.

“I can’t believe you’re politicizing a tragedy,” Gardner snapped back.

The high-stakes race is Udall’s first re-election bid after taking office in 2008 during a banner year for Democrats.

Most polls show Gardner tied with Udall.

The candidates debated Saturday evening in Grand Junction at an event hosted by Club 20, an influential western Colorado advocacy group.

Republicans have made Obama’s low approval ratings and the country’s health-care overhaul a big issue in the campaign.

“You promised the American people that if you liked your health-care plan, you can keep your health-care plan,” Gardner asked Udall. “When did you know that that promise was not going to be kept?”

Udall responded by blaming insurance companies for “not keeping faith with the intent of the law.”

Democrats, meanwhile, are seeking to paint Gardner as being against reproductive rights.

“How can women and families trust you? Why are you getting between women and their doctors?” Udall asked Gardner.

Gardner responded by saying he supports expanding access to over-the-counter birth control for women.