He was only supposed to fill in for six weeks.

Eighteen months later, Bob Schieffer finally wraps up his gig as the interim anchor of the "CBS Evening News" this evening when he helms his last broadcast.

For Schieffer, who is passing the baton to incoming anchor Katie Couric, the last 18 months have come as an unexpected yet pleasurable stint; one in which he managed to leave his mark, despite the temporary nature of his appointment.

Under his watch, ratings at the third-place broadcast climbed upward — the only network newscast that can make such a claim this season — and the internal angst caused by former anchor Dan Rather's controversial report on President Bush's military service finally dissipated.

"I'm really proud of what we've accomplished," Schieffer said in an interview last week. "We were in a very hard place, and I do believe that we've got the train back up on the tracks and running in the right direction."

He has endorsed the selection of his successor, whom he hopes to have on the broadcast this evening for a symbolic passing of the baton.

Couric "has attracted this enormous amount of attention, which I think in the end may raise the ratings of all the newscasts," Schieffer said. "I think we have a chance now to be No. 1. We're already a first-rate news organization."

One of the first things Schieffer did when he took over the anchor desk was to introduce more back-and-forth with the correspondents, quizzing them in his trademark folksy style.

"Before him, there was this air of omniscience in the way the program was produced," said former CBS News President Andrew Heyward. "Bob kind of clambered down off the pedestal."

Schieffer, who has continued moderating the Sunday program "Face the Nation," said he would miss the anchor desk, but said he's content that it was a short-term assignment.

"If this had happened 10 years ago, I would have liked to have had the job," he admitted. "But at this point in my life, I wouldn't have done it for an extended period of time. You don't build something that you want to last another 10 or 15 years around someone my age."

One thing he won't miss is the schedule. Every Friday night, he flew back home to Washington, where he spent Saturdays preparing for Sunday's "Face the Nation." He returned to New York every Monday on the 7:30 a.m. shuttle.

This week, he goes back to Washington for good, where he will reassume his duties as chief Washington correspondent. Schieffer will continue moderating "Face the Nation" and expects to appear on the evening news at least once a week doing commentary and news analysis.

"This is going to be for me, at this stage of my life, the perfect assignment," Schieffer said.

Though he has contemplated retiring in February on his 70th birthday, CBS News President Sean McManus asked Schieffer to stay on through the 2008 election — something he's leaning toward, for now.