Retired Gen. Wesley Clark’s Democratic presidential campaign will get a major boost on Capitol Hill tomorrow when he receives the endorsement of Senate Finance ranking member Max Baucus (Mont.).

Baucus is the first Senator not from Clark’s homestate of Arkansas to announce support for his presidential candidacy and may help restart a campaign that has lost significant momentum in Congress and in key early primary states in recent weeks.

Baucus and Clark had no prior relationship, according to knowledgeable sources; the Montana Senator was attracted to Clark’s candidacy because he believes the general is the most electable candidate in the current nine-person field.

Sen. John Breaux (La.), one of the leading moderates in his party, has long been viewed as a potential supporter of Clark but has not backed him yet. Sources familiar with the situation indicate that the Louisiana Senator is firmly in Clark’s camp, however.

Baucus’ endorsement is a tacit slap at his colleagues — Sens. John Kerry (Mass.), Joe Lieberman (Conn.) and John Edwards (N.C.) — who have been running for the nomination for much of this year. Clark officially entered the race in late September.

Reps. Richard Gephardt (Mo.) and Dennis Kucinich (Ohio) as well as former Vermont Gov. Howard Dean, former Illinois Sen. Carol Moseley Braun and the Rev. Al Sharpton are also seeking the nomination.

Baucus plans to open up to Clark a significant fundraising network that helped him raise and spend better than $6 million in his 2002 re-election race as well as his political operation — led by Jeff Forbes, the minority staff director on the Finance Committee.

Baucus becomes only the third nonhomestate Senator to weigh in on behalf of a presidential candidate and the first ranking member of a full committee to do so. Sen. Dianne Feinstein (Calif.) is backing Kerry while Sen. Tom Carper (Del.) is behind Lieberman.

Interestingly, Clark has called for a partial rollback of the tax-cut package that Baucus supported in 2001. Clark favors repealing the cuts granted wealthy Americans while keeping in place those received by the middle class.

Baucus took considerable political heat for allegedly cutting a deal favorable to President Bush and GOP leaders at the time, but in the end his willingness to cross party lines paid off as he won a stunning 63 percent victory in strongly Republican Montana.

Baucus’ decision to endorse Clark may be another example of political pragmatism by the Montana Democrat, who regularly faces charges that he is a “liberal” in his contested re-election races.

The vast majority of Clark’s Member support to this point has come from the moderate to conservative wing of the party.

Of the 11 House Members backing Clark, six are members of the Blue Dog Coalition including Rep. Marion Berry (Ark.), who has been one of Clark’s most outspoken advocates on the Hill. Clark is expected to pick up the endorsement of Rep. Anthony Weiner (N.Y.) in the coming days, adding another potent fundraiser to his cadre of Hill supporters.

Reps. Rahm Emanuel (Ill.) and Charlie Rangel (N.Y.), two of the most active and able fundraisers in the Democratic Caucus, have taken lead roles with the Clark campaign.

After an initial splash in Washington, however, Clark’s momentum — and the pace of his Congressional endorsements — have slowed considerably.

Clark held an information session on Sept. 30 that was attended by roughly 65 House Members, a group which spanned the ideological and geographic breadth of the Caucus.

Since then his campaign has been battered by the loss of its original campaign manager, the campaign’s initial indecision on whether to support the president’s $87 billion supplemental package for Iraq, and yesterday’s decision by the American Federation of State, County and Municipal Employees to endorse Dean.