DENVER -- An ad attacking Democratic U.S. Senate candidate Mark Udall misleads voters about his record on cutting taxes, a 7News analysis of the ad found.

"Mark Udall voted for higher taxes at least 50 times," the ad claims.

To back up this charge, ad producers provide a list of votes, but the problem is that many are multiple votes on the same bills. Congress often has multiple votes on one measure.

So it is misleading to imply that Udall voted to raise taxes 50 different times.

The Udall campaign said the congressman voted at least 60 other times to cut taxes for middle class people.

"Udall is fighting for the biggest tax increase in history," the ad says.

The ad backs this claim up with Udall's vote not to extend President George W. Bush's tax cuts. While it's true that he voted against extending the tax cut as many other Democrats did, it is fiction to say he is fighting for the biggest tax increase in history.

"Udall ... voted to block bipartisan energy reforms that could lower gas prices," the ad says.

These claims are fact. Udall opposed a tax holiday that would have temporarily suspended the federal gas tax, which would have saved drivers about 20 cents a gallon for the summer. Udall says he wants a permanent solution to the energy crisis.

And Udall has opposed drilling in environmentally sensitive areas, saying oil companies are not using all the leases where they are currently allowed to drill.

An additional note: The ads are being run by a group called Coloradans for Economic Growth. They declined -- and federal law does not require -- that the group disclose its donors because they are organized as a nonprofit.

The group said they are independent from Udall's opponent, Republican Bob Schaffer. However, they do list Schaffer as an "outstanding leader" on their web site while attacking Udall.