Sen. Amy Klobuchar holds 20-plus-point leads over her three largely-unknown Republican challengers and the failed presidential bids of Republicans Tim Pawlenty and Michele Bachmann have damaged their support in Minnesota, according to a new poll released today.

Klobuchar has a 61 percent approval rating, according to Public Policy Polling, a Democratic polling agency known for its accuracy. PPP said it’s polled only five current Senators with higher approval ratings. She has broad support among Democrats (89 percent) and independent voters (59 percent). Right now, she would receive around 55 percent of the vote in head-to-head match-ups against all three Republicans looking to challenge her in November.

More than 80 percent of those polled said they have no opinion on any of those Republicans: former state Rep. Dan Severson, St. Bonifacius City Councilman Joe Arwood and activist Anthony Hernandez. PPP expects the margins between Klobuchar and her challengers to tighten slightly before the November elections, but it still considers her “close to unbeatable” in 2012.

Klobuchar would also defeat Rep. Michele Bachmann (58-35) and former Gov. Tim Pawlenty (54-39) in hypothetical head-to-head match-ups. After their failed presidential bids, Bachmann and Pawlenty have negative support in Minnesota — only 34 and 39 percent hold favorable opinions of them respectively. Fifty-seven percent of respondents said they do not want Bachmann to run for re-election to the U.S. House of Representatives, and 51 percent said they would not support Pawlenty if he ran for state-wide office again.

Sen. Al Franken, meanwhile, has a 49 percent approval rating. He is up for re-election in 2014 and would lead both Pawlenty (49-43) and Bachmann (54-39) in hypothetical match-ups. The field of Republicans looking to challenge Franken is expected to be large.

Public Policy Polling surveyed 1,236 Minnesotans over the weekend. The agency plans on releasing 2012 presidential election figures later this week. Today’s results can be found here.

Devin Henry can be reached at dhenry@minnpost.com. Follow him on Twitter: @dhenry