Sen. Michael Bennet has widened his lead in the Democratic primary, but former Lt. Gov. Jane Norton’s advantage in the GOP primary has narrowed, according to a Public Policy Polling survey conducted Friday through Sunday.

Of the 442 voters surveyed who said they were likely to vote in the August Democratic primary, 46 percent backed Bennet and 31 percent preferred former state Speaker Andrew Romanoff. A March PPP poll pegged Bennet’s lead at 40 percent to 34 percent.

Bennet has used his big fundraising advantage over Romanoff to air television commercials that promote an outsider message of “cleaning up” a “broken” Washington, D.C. Romanoff has tried to link Bennet to Wall Street.

Bennet, who had been the superintendent of the Denver Public Schools until early 2009, was appointed to the Senate after then-Sen. Ken Salazar (D) became President Barack Obama’s secretary of the Interior.

Of the 448 likely Republican primary voters surveyed, Norton led Weld County prosecutor Ken Buck 31 percent to 26 percent, down from the 34 percent to 17 percent advantage she had in March.

Norton has raised far more money than Buck and has support from numerous GOP Senators. But she spent almost as much as she raised in this year’s first quarter, and Buck got a boost when he narrowly outpolled Norton at nonbinding GOP precinct caucuses in March. He has the backing of the Senate Conservatives Fund, an organization headed by Sen. Jim DeMint (R-S.C.)

Norton had a favorability rating of 34 percent and an unfavorability rating of 23 percent. For Buck, the figures were 32 percent favorable and 14 percent unfavorable.

Several lesser-known Republicans are seeking the nomination, and nearly three in 10 Republican voters said they were undecided about a candidate.