Mayor Mitch Landrieu made it official last week when he formally endorsed Cynthia Willard-Lewis in the special election for Arnie Fielkow's old at-large seat on the City Council. His nod to Willard-Lewis had been expected for weeks. He's backing her for several reasons.

  As he mentioned in his endorsement speech to Willard-Lewis' supporters at the New Orleans Healing Center in the Faubourg Marigny, he wants another "partner" on the council, particularly in this all-important at-large seat.

  The two at-large council members take turns serving as council president, and the president appoints committee members and committee chairs. More than ever, the work of the council — as in most legislative bodies — is done in committee. Having someone he can count on with that kind of power is important to an activist mayor like Landrieu.

  Willard-Lewis' opponent, District B Councilwoman Stacy Head, is also a reformer, but she's not an automatic Landrieu vote. She's just as likely to question his budgets, his contracts and his appointments as she did former mayor Ray Nagin's. Landrieu, who can get testy when challenged, would prefer a softer touch in the presiding officer's chair — though he took care not to say anything critical of Head during and after his endorsement of Willard-Lewis.

  Landrieu's endorsement also repays a political debt. During his racially charged (though not by him) 2006 campaign against Nagin, Landrieu needed all the black support he could get. Willard-Lewis, who is black, went door-to-door for him — and with him — in her district. A seasoned pol like Landrieu doesn't forget that.

  On matters of race, Landrieu also needs to shore up his base in the black community right now. A succession of scandals at NOPD — from indictments to controversial shootings of black civilians — has understandably put many African-American citizens on edge politically. As mayor, it's part of Landrieu's job to assure them that City Hall is not ignoring their concerns.

  And, of course, the history of "power sharing" or electing one white and one black at-large council member likewise factors into this election and Landrieu's decision. He said even before qualifying opened that he hoped Fielkow would be succeeded by a qualified African-American.

  Those are the mayor's principal reasons for backing Willard-Lewis. The big question now is, in this final week of the campaign, what's the impact of his endorsement?

  I doubt that Landrieu will change many minds. Most if not all New Orleans voters already know which candidate they prefer — but most will not take the time to go vote this Saturday.

  That's not to say Landrieu's endorsement is meaningless. Far from it.

  I think it equalizes things.

  Until last week, Head held a slight advantage in the polls. Moreover, given the historically higher turnout among white voters, many felt the race was hers to lose. Landrieu's enthusiastic support of Willard-Lewis gives her campaign some needed momentum, some traction, particularly in light of Head's fundraising advantage. Head outspent Willard-Lewis by a margin of more than 11-1 in the primary.

  But Willard-Lewis is one of those unusual candidates who defies the conventional wisdom about money and politics. She garnered 34 percent of the vote in the primary with just $25,000. Head raised nearly $300,000 and got 43 percent. Obviously Willard-Lewis has a deep reservoir of support that money doesn't affect.

  And with turnout likely to be less than 15 percent — maybe barely 10 percent — the deciding factor in this contest will be turnout. Both candidates will be doing all they can this week to remind — and motivate — their voters to go to the polls on Saturday.

  If nothing else, Landrieu gave Willard-Lewis' base a reminder last week. In doing so, he may have neutralized Head's fundraising edge and equalized both candidates' chances.