Former Alaska Gov. Tony Knowles (D) added another top-level political hand to his Senate campaign this week.

Jim Messina has taken a leave of absence from his position as chief of staff to Sen. Byron Dorgan (D-N.D.) to serve as Knowles’ Senate campaign director.

Messina joins longtime Knowles aide Leslie Ridle in overseeing the Democrat’s effort to unseat Sen. Lisa Murkowski (R).

In an acknowledgement to how tight the race is expected to be — and the pivotal role it could play in determining which party controls the Senate — Dorgan was willing to let his chief head out to the Last Frontier, said an informed source.

Dorgan faces only nominal competition in his re-election bid from attorney Mike Liffrig (R) this fall, so party officials decided Messina’s skills could be put to better use in Alaska, the source added.

Cara Morris, spokeswoman for the Democratic Senatorial Campaign Committee, said Messina is “highly respected at the DSCC for his work in the field and on the Hill. He brings that overall experience to [his] campaigns.”

“This is going to be an extraordinarily close race and we are very excited to have Jim here helping out,” added Matt McKenna, spokesman for Knowles.

McKenna cited Messina’s experience in Western campaigns as a chief reason for hiring him.

Messina ran the 2002 re-election campaign of Sen. Max Baucus (D-Mont.) in which Baucus won 63 percent of the vote. Messina also worked on Baucus’ successful 1996 campaign.

In between those campaigns, Messina served as chief of staff to Rep. Carolyn McCarthy (D-N.Y.).

As campaign director, Messina will “lend his expertise to every facet of this campaign,” McKenna said.

Messina comes aboard at a time when Knowles is being mocked in a National Republican Senatorial Committee television spot in which the GOP tries to tie him to “Eastern” politicians who “wouldn’t know a caribou if it dropped in for a bowl of Boston clam chowder.”

The ad implies that Knowles would be joining forces with national Democrats who oppose oil drilling in the Arctic National Wildlife Refuge — a position that is anathema to most Alaskans.

Knowles has decried the ads as being negative and untrue — he is an ardent advocate of ANWR development — and has scolded Murkowski for not denouncing third-party advertisements.

This is the second buy of the campaign in which a group other than the candidate has run ads to boost Murkowski.

Knowles pledged to disavow anybody who might try to run ads on his behalf and promised to tell groups such as the DSCC that he does not want their help with political advertising.

Murkowski’s campaign spokesman has said he would see how the race develops before believing Knowles’ pledge.

A Democratic source said that Messina’s expertise with Western campaigns and rural issues should help Knowles counter attacks such as the one concerning ANWR.

Resource development, gun rights and environmental issues are major factors in Montana and North Dakota as well as Alaska, the source said.

Perhaps the gun issue is better left to Knowles’ Alaska staff, however, as Messina worked for McCarthy — the widow of a victim of gun violence who has made gun control her signature issue.

Mary Ann Akers contributed to this report.