That's virtually unchanged from the survey PPP conducted in December which found Udall leading tea party favorite Ken Buck by just 4 percentage points. Buck, who has made his share of eyebrowing raising comments, dropped out of the Senate race so he could run for Gardner's seat instead.
National Republicans argue that Garnder is a stronger candidate than Buck and his decision to run for Senate puts Udall's seat in play.
Udall holds wider leads in head-to-head matchups with the other candidates in the Republican primary, the poll found. Against state Sen. Owen Hill Udall leads 43 percent to 38 percent and against state Rep. Randy Baumgardner Udall leads 44 percent to 37 percent.
Hill actually dropped out on Tuesday. In announcing his decision not to run he said that Gardner has "the best chance of beating Mark Udall" in November.
The PPP survey was conducted among 589 Colorado voters from March 13 to March 16. It had an overall margin of error of plus or minus 4.1 percentage points and plus or minus 6.1 percentage points among just Republicans.