HELENA, Mont. (AP) -- U.S. Sen. Jon Tester of Montana isn't happy about a Republican attack advertisement portraying him with all five fingers on his left hand - even though he lost three fingers in a childhood accident with a meat saw.

Tester, a first-term Democrat, is being challenged in his 2012 re-election by U.S. Rep. Denny Rehberg, one of the best-known Republicans in Montana. Polls have shown the race very tight, and it is expected to be among the most watched in the nation as the parties vie for control of the U.S. Senate.

Both Tester and Rehberg are expected to get plenty of outside help and money in a race that is already very heated early, and is expected to dominate Montana politics for the next 13 months.

The most recent hullabaloo comes over an ad from the National Republican Senatorial Committee that portrays Tester as cozy with Washington, D.C., lobbyists. It also shows a photo of Tester happily greeting President Barack Obama, no doubt aimed at sending a message to Montana voters about the ties between the two.

But the edited photo erroneously portrays Tester as having a left hand with all five fingers. Three of those fingers were taken when Tester, as a child, was working in the family farm's butcher shop.

Tester spokesman Aaron Murphy said "from the made-up photo to the misleading message, the whole ad is an inaccurate picture of Jon and his record of transparency and accountability."

Republicans said Thursday that someone else's left hand was accidentally left in the photo when people in the background were cut out to show just Tester and Obama. The NRSC argues the mix-up doesn't change the message of the ad.

The Republicans have been hammering Tester for taking a lot in campaign donations from lobbyists even though he campaigned in 2006 against the corruption of Washington D.C. They have also been tying him to a president whose popularity has waned in the red-leaning state of Montana.

The NRSC alleges Tester, with his criticism of the photo, wants to shift the conversation away from the content of the ad.

NRSC spokesman Chris Bond said "it's understandable that his campaign would want to distract voters with a phony controversy."

Tester's camp said the senator has made several moves to increase accountability standards in Washington D.C, such as by refusing meals and travel paid for by lobbyists and by becoming the first member of Congress to publicly post his schedule.

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