On the eve of Election Day, a Quinnipiac University poll of likely voters released Monday shows both Colorado’s race for governor and U.S. Senate too close to call.

The poll found U.S. Rep. Cory Gardner’s lead over Democratic incumbent Sen. Mark Udall is shrinking compared with numbers released last week. Gardner is leading Udall with 45 percent of the vote against 43 percent of the vote, the Monday poll showed.

A Quinnipiac poll on Thursday showed Gardner leading with 46 percent of the vote against Udall’s 39 percent of the vote.

Monday’s poll leaves the Senate race well within the 3.4 percentage point margin of error.

“Not so fast, say the latest numbers as U.S. Rep. Cory Gardner’s comfortable lead over Sen. Mark Udall becomes a race too close to call,” said Tim Malloy, assistant director of the poll. “What looked like a GOP lock on a coveted Senate seat in a target state heads down to the wire with no clear leader.”

In the governor’s race, Republican challenger Bob Beauprez has 45 percent of likely votes while Democratic Gov. John Hickenlooper has 43 percent, the poll found.

“Colorado Gov. John Hickenlooper will have to count on an aggressive final hour ground game and a bump from the undecideds to keep the state’s top job, but it can go either way,” Malloy said.

Stay with The Denver Post throughout the week for our ongoing, comprehensive coverage of Election 2014.

Jesse Paul: 303-954-1733, jpaul@denverpost.com or twitter.com/JesseAPaul