Senate Majority Leader Harry Reid is trailing a top Republican challenger by 11 points ahead of next year's election, according to a new poll. The Mason-Dixon Polling and Research survey, reported Sunday in the Las Vegas Review-Journal, showed GOP candidate Danny Tarkanian leading Reid by 49 percent to 38 percent in Nevada. Tarkanian is a former basketball player for the University of Nevada-Las Vegas and recently announced his candidacy. The new poll also showed Sue Lowden, chairwoman of the Nevada Republican Party and a possible candidate, leading Reid by 45 percent to 40 percent. The sagging numbers come at a time when congressional Democrats are facing tough questions from constituents on their health care reform proposals. Reid has a lot of time to make up the difference in the polls. But of the top Democrats in Congress, he is perhaps the most vulnerable. While House Speaker Nancy Pelosi is from a solidly liberal district in California, Nevada is not so dependable for Democrats. Nevada's other senator, John Ensign, is a Republican. But he's got his own set of problems, after admitting an affair with a former staff member. The new poll showed 37 percent of voters would vote against him, while 30 percent would re-elect Ensign. Twenty-three percent said they'd consider a challenger. Ensign does not face the voters' verdict until 2012. The poll of 400 registered Nevada voters was taken Monday and Tuesday. It had a margin of error of 5 points.