Gov. Mark R. Warner explained his sad predicament last week to parents of preschoolers in Hampton, Va., some of them evacuees from the Gulf Coast.

"For those of you from Louisiana and Mississippi, we have this crazy rule that says in Virginia, you can only run for governor one time and then you've got to get out. You can't run for reelection," Warner said. He motioned toward Lt. Gov. Timothy M. Kaine, seated to his left. "So this is the guy I hope will take my job."

Not exactly "the next governor of the great commonwealth of Virginia." But that came later, at a sold-out dinner in Richmond filled with establishment Democrats, business elite and a smattering of Republicans, the kind of group Warner put together four years ago to break the GOP hold on the governor's office.

"Every step along the road, I've had a partner in Tim Kaine," Warner told the group. "This is the person, let me be absolutely clear, that will continue the progress."

If there were questions at the beginning of the campaign about how hard Warner, 50, would work to help Kaine, from whom he kept his distance when both ran statewide in 2001, they have been answered. Warner was there for Kaine's announcement, walking the parade route with Kaine at the traditional Labor Day campaign kickoff, and he headlined a million-dollar fundraiser in Northern Virginia and the $500-a-plate dinner in Richmond on Wednesday.

Kaine's aides said Warner and Kaine will campaign together every week until the Nov. 8 election, and the two will be side by side for the last four or five days of the campaign. And by the end of the weekend, voters across the state will be seeing a 30-second television spot in which Warner appeals for Kaine's election.

How close is too close? At what point might Kaine's efforts make him seem less like Warner's logical successor and more like his little brother? If there is a line, the Kaine campaign has not found it.

"Throughout this entire campaign, Tim Kaine has been making the case why he wants to be governor," said Mo Elleithee, Kaine's communications director. "But a big part of what this campaign is about, is about continuing the success of the last four years."

Warner is "the governor, and they're only candidates, so he is bound to overshadow them now," said Steve Jarding, a political consultant who managed Warner's campaign and now spends much of his time teaching politics at Harvard University. "This guy [Warner] has so many pluses and is so popular in really every part of the state -- you want [your candidate] to be associated with that."

He said that if any campaign manager "had a moment of angst about that, it would be fleeting."

Kaine's Republican opponent, Jerry W. Kilgore, passes off Warner's support as simple partisanship.

"There is no evidence that Mark Warner's relative popularity transfers to Tim Kaine," said Tim Murtaugh, Kilgore's press secretary. "The problem with that tactic is that Mark Warner's name is not going to be on the ballot, and Tim Kaine's will be."

He added, "Just because you hang around with the quarterback doesn't make you the quarterback."

A day of campaigning by Democrats last week demonstrated that Warner likes his big-man-on-campus role. At an Alexandria school to promote Kaine's idea of greatly expanding early childhood education, Warner talked mostly about his public-private partnerships to turn around struggling schools and his initiative to get health insurance for poor children. He jokingly found a book for Kaine in the school library: "Curious George Takes a Job."

Afterward, he commandeered the entourage traveling with the candidate to walk to Five Guys for cheeseburgers, while Kaine's aides worried about being late for the next stop. Warner startled a table of four that didn't notice him quite quickly enough: "Hey, I'm the governor." He shook every hand in the place.

In Hampton, it was competitive campaigning. When a parent in the audience at the Hampton school said she did not speak English well, Kaine asked where she was from and continued to talk with her in Spanish. Warner quickly chimed in, showing that he, too, speaks Spanish.

Warner admits that he is reluctantly giving up the job. "It's doubly hard, because on a personal level, I really like this job, and I'm, I think, a little bit better at it" than when he started, he said in an interview later. "I'd like to have some of that first year [of his term] back, you know, and put it on the back end."

Being governor was Warner's first time holding public office, after years in business. "It's not like I'm used to turning the reins over," he said.

"I think Kaine is right to try to convince voters that he can be the second Warner administration that the constitution doesn't allow," said Mark J. Rozell, a public policy professor at George Mason University. "On the other hand, he has to find a way to be his own man."

Public and private polls show Warner with extraordinarily high approval ratings. A Washington Post poll taken Sept. 6 through 9 showed that 76 percent of registered voters approve of the way Warner is handling his job and that 65 percent think the state is heading in the right direction. Those polled were evenly split on whether the state needs a governor who "can get the state going in a new direction" or who will "keep the state going in the same direction we're going."

That reflects voters' views, Warner said, that "people always think things can be better, and they can always be better."

"I'm proud of what we've done, but I know that [Kaine has] got to have his own agenda, his own way that he takes what we've done and tries to build on it. And I've got to acknowledge that it might not be exactly the same way that I'd build on it."

It would be a stretch to say that Warner and Kaine have always been seen as a political team. The two attended Harvard Law School at the same time but were not friends. And because Virginia elects its governor and lieutenant governor separately, Kaine had no official role in the Warner administration. His only constitutional duty was to preside when the state Senate was in session.

Kilgore complained at a recent debate that Kaine has been burnishing his credentials. "He broke ties in the Senate, folks," Kilgore said. "That's all he did."

But it is Kilgore who criticized the "Warner-Kaine" administration in a fundraising letter he sent in 2004. Kilgore is a staunch opponent of the budget deal, which Warner engineered and Kaine supported, that cut some taxes and raised others and produced nearly $1.5 billion in new revenue for a two-year period.

Last week, Kilgore annoyed Warner by saying that the state had been tardy in drawing federal funds for highway construction and that some projects had been delayed as a result. Kilgore's accusation was widely viewed as a blunder by the Richmond political establishment when transportation experts disputed his analysis, and his staff could not cite a specific project that had been postponed.

Warner described Kilgore's charge as "absolutely, factually untrue" but is otherwise muted in criticism of him or the other party. He usually refers to Kilgore as "Tim's opponent," and is careful, in a state in which Republicans still have the advantage, to avoid alienating the other side.

"Turning this into a sort of vitriolic, partisan thing in the last 40 days isn't me," Warner said, "and would probably do more to hurt Tim than to help him."

Gov. Mark R. Warner concedes that giving up office is hard.