OTTAWA - Former astronaut Marc Garneau has decided to run for the federal Liberals after all.

Only two weeks ago Garneau, widely deemed a star recruit, announced that he was quitting politics because he felt he was not part of Liberal Leader Stephane Dion's vision.

But now Dion is set to announce Friday that he's appointing Garneau to carry the party's banner in the Montreal riding of Westmount-Ville-Marie, one of the safest Grit bastions in the land.

The riding's Liberal incumbent, Lucienne Robilliard, has decided not to seek re-election.

Garneau resigned as head of the Canadian Space Agency to run for the Liberals in the 2006 election. He ran in a difficult Quebec riding -- Vaudreuil-Soulanges -- and lost.

He had hoped to run again in a safer riding but was rebuffed by Dion when he expressed interest early this year in the Montreal riding of Outremont, a longtime Liberal fortress. Dion eventually hand-picked a candidate for that riding -- academic Jocelyn Coulon -- who suffered a humiliating defeat in a byelection last month.

When Robillard announced last May that she wouldn't seek re-election, Garneau set his sights on Westmount only to have Dion once again suggest that he had someone else in mind. Some Liberals speculated that Dion was punishing Garneau for backing Michael Ignatieff in last year's leadership contest.

Garneau announced his decision to quit politics last month, only a week after the party's devastating loss in Outremont. He confirmed that Dion's apparent indifference to his candidacy was one of the primary reasons for throwing in the towel.

The news added to the perception that the Liberals were in freefall in the province and led to doubts that Dion would be able to attract any high-calibre Quebec candidates.

"Sometimes, between two people, it just doesn't work out and I'm not necessarily part of somebody's vision,'' Garneau said at the time.

He seemed to rule out a comeback any time soon, saying: "I've gone into the private sector now for as long as I can see in the future.''

That turned out to be two weeks, during which Dion spent a lot of time persuading Garneau to change his mind.

Insiders say Dion was never indifferent or hostile towards Garneau. He simply had not turned his attention to the matter of his candidacy until recently, being more focussed on the three Quebec ridings where byelections were held last month.

Insiders credit Dion's new principal secretary, Johanne Senecal, for striking the rapprochement between the two men.

Garneau's about-face is a ray of good news for Dion at the end of an otherwise grim week.

Dion's Quebec lieutenant and the director general of the party's Quebec wing quit just hours before the Harper government's throne speech was unveiled. Two Montreal MPs turned down the lieutenant's job before Dion finally tapped Liberal ranks in the Senate to fill the post.

With the party in evident disarray, Dion was compelled to announce Wednesday that Liberals will abstain on the throne speech in order to avoid defeating the government and forcing an election.