HELENA — The U.S. Senate’s top Democratic leader on Thursday promised Senate candidate Jon Tester a seat on the powerful Senate Appropriations Committee “as soon as possible’’ if Tester defeats Republican incumbent Conrad Burns next month.

At a press conference in Billings, Democratic Sen. Max Baucus released a statement from Senate Minority Leader Harry Reid, D-Nev., pledging to give Tester a coveted seat on Appropriations Committee, regardless of whether Democrats wrest control of the Senate from Republicans.

“Jon Tester is a man of integrity and a man that I look forward to working closely with in the U.S.Senate,’’ Reid’s statement said. “Jon has proven to be a great leader in Montana, and I know he will bring his values of hard work and honesty to Washington.’’

The announcement was designed to blunt Burns’ key campaign theme — that he “delivers for Montana.’’ Burns has sat on the Appropriations Committee since 1994 and has taken credit for bringing $2.2 billion in federal funds to Montana during his 18-year Senate tenure.

Less clear was exactly when Tester would join the Appropriations Committee if he wins. Even Reid’s spokesman, Jim Manley, conceded it would be “somewhat unusual’’ for a freshman senator to be appointed to that panel.

All 13 Democrats on the panel are expected to return, although Democrats would get to expand their numbers if they take control of the Senate.

At a press conference in Billings, Baucus, Tester and Gov. Brian Schweitzer hailed Reid’s commitment.

“This is big news,’’ Baucus said. “This is really important. This is going to help Montana even more. The main thing is Jon’s the man. Jon will be on the Appropriations Committee. He will get even more jobs for Montana.’’

Baucus, a close ally of Reid’s, said Tester is the lone Democratic Senate candidate to gain a commitment from Reid for a slot on the Appropriations Committee

Burns’ campaign pooh-poohed the announcement.

“I think it’s so desperate that it’s almost pathetic,’’ said Erik Iverson, who heads the Burns campaign. “Conrad Burns already has a seat on the Appropriations Committee, and he has 18 years of experience and seniority in the Senate to get the job done.’’

Iverson said Montanans won’t vote to risk Burns’ senior seat on the committee “in exchange for a hollow promise’’ that Reid might someday put Tester on the panel.

It took Burns six years to gain a seat on the panel.

Iverson also suggested Reid’s word is “pretty much worthless’’ because the Democratic Senate leader is “involved in a land scandal in Las Vegas where he made over a million bucks on land he didn’t even own.’’

Asked to respond, Reid’s spokesman Manley refused to address the allegations, saying, “Senator Reid looks forward to working with Jon Tester in the U.S. Senate.’’