WASHINGTON – As New York’s mayoral race takes shape, Senator Schumer finds himself in the delicate position of choosing between his protege, his wife’s employer, and the support of many minority voters in the city.

The senator’s wife, Iris Weinshall, works as transportation commissioner for the incumbent Republican mayor, who is running for re-election. Mayor Bloomberg crossed party lines to endorse Mr. Schumer’s Senate re-election bid last fall, and he warmly praised the senator’s “hard work,” declaring that he had “delivered” for the city.

Adding to the Bloomberg connection, one of the senator’s aides, Stu Loeser, has defected to the mayor’s office from the senator’s famously kinetic press office. Mr. Loeser began putting his Schumerian public relations experience to work yesterday in the service of the mayor’s re-election bid.

Mr. Loeser declined to discuss his job switch, but the move has highlighted the tangle of personal ties that bind the senior senator to the mayoral race.

The candidate with the most at stake in a Schumer’s endorsement is Rep. Anthony Weiner, a Democrat of Queens and a friend and protege of the senator.

Mr. Weiner began his political career as a Schumer intern, and during six years of loyal service he rose through the ranks, holding such unglamorous positions as computer operator, legislative aide, and district office coordinator before he ran for a seat on the City Council.

Mr. Schumer endorsed Mr. Weiner in that race, and again when he ran for Congress.

Mr. Weiner calls the senator his “mentor and friend” and has copied – some say cloned – the senator’s populist political style and tireless public relations operation.

But while Mr. Schumer has had cordial relations with the mayor’s office, Mr. Weiner’s strategy has been to connect Mr. Bloomberg to every perceived fault of the Bush administration.

Mr. Schumer has not given any indication of what role, if any, he will play in the race. Political wisdom says he should stay above the fray, while personal loyalties may make that difficult, strategists say.

“The senator is clearly in a complex situation, given the fact that his wife is one of Mayor Bloomberg’s commissioners, and the senator feels that in many areas the mayor has done a good job,” said a New York political consultant, Scott Levenson, who has advised Democratic candidates in state and local races. On the other hand, he said, “no one competes” with Mr. Weiner in terms of personal closeness to Mr. Schumer.

“Senators often sit out competitive Democratic primaries because they don’t want to choose among friends,” noted Mr. Levenson.

If Mr. Schumer kept his distance from the contest, he would be denying Mr. Weiner, perceived as a long-shot candidate, a “huge” endorsement.

Asked whether Mr. Weiner is expecting an endorsement from his mentor, he said through his spokesman, Anson Kaye, “I haven’t asked.”

Adding to the complicated mix are other Democratic mayoral hopefuls whose minority constituents Mr. Schumer might be loath to offend.

“If he gets involved in the primary, he could only create ill will,” said another New York political consultant, Henry Sheinkopf.

The senator may be well advised to stay out of the contest until a Democratic candidate is chosen in September’s primary election, and then decide how heartily to campaign on that candidate’s behalf leading up the general election in November, he said.

New York’s junior senator, Senator Clinton, has studiously avoided openly endorsing fellow Democrats in past races, be it for the presidency or for the chairmanship of the Democratic National Committee.

Mr. Schumer might be advised to follow her lead, some said.

“It would be smart for Chuck, considering that [Bronx Borough President] Fernando Ferrer will be the standard-bearer for an increasingly large electorate and [Manhattan Borough President] C. Virginia Fields for another important electorate,” said Mr. Sheinkopf, referring to Hispanic and black voters.

“Schumer’s strength has been in alienating the few and doing service to the many,” he said.

Another mayoral hopeful is City Council Speaker Gifford Miller. A recent Quinnipiac University poll showed Mr. Ferrer tied with Mr. Bloomberg in a head-to-head race for mayor.

Mr. Schumer’s new spokesman, Israel Klein, declined to discuss the senator’s potential role in the mayoral race, or the significance of Mr. Loeser’s job change.

“I don’t think there is anything to read into that,” Mr. Klein said. He said it’s “too early to know right now” whether Mr. Schumer would endorse a candidate.

Asked whether the senator would show special preference for Mr. Weiner, who learned politics at his knee, Mr. Klein replied, “I’m not going to comment on knees.”