Mayor Bloomberg showered the Bronx president, a possible candidate to replace him, with praise yesterday, and the borough chief returned the favor by calling the mayor “Mr. President.”

The Bronx leader, Adolfo Carrion, is a likely Democratic candidate in 2009, but he and the Republican mayor could not have appeared closer at separate ribbon-cutting ceremonies yesterday in the South Bronx.

Playing off Mr. Bloomberg’s rumored aspirations for the White House, Mr. Carrion referred to the mayor as “Mr. President” when he stepped to the podium at the Bronx Museum of the Arts, where officials were celebrating the completion of a $19 million expansion. He quickly corrected himself, to laughter from the crowd.

Later in the day, at the opening of a five-acre waterfront park in Hunts Point, Mr. Carrion made the slip again, claiming it was accidental.

Mr. Bloomberg has repeatedly denied any presidential ambitions, even as his chief political strategist, Deputy Mayor Kevin Sheekey, has publicly promoted a White House run.

At both events, Mr. Bloomberg was even more effusive in complimenting Mr. Carrion. In addition to calling the borough president the city’s no. 1 elected Yankee fan, Mr. Bloomberg, at Barretto Point Park, introduced Mr. Carrion as “the greatest advocate for the Bronx, and in all fairness, the person who’s made the most difference in my memory in this borough.”

The mayor made no mention of Mr. Carrion’s predecessor, Fernando Ferrer, who served as president of the Bronx between 1987 and 2001. Mr. Bloomberg repeatedly criticized Mr. Ferrer’s record in office during last year’s mayoral campaign, which Mr. Bloomberg won in a landslide.

Mr. Carrion endorsed Mr. Ferrer in that race, but he referred to Mr. Bloomberg yesterday as “our great mayor.”

A spokesman for Mr. Carrion, Michael Murphy, said the mayor and the borough president “have always had a great relationship. They share similar views about the positives of a five-borough program for economic growth, and they both understand that the best social program is a job.”

The cozy relationship between Messrs. Bloomberg and Carrion is symptomatic of the current political climate in the city, a Democratic political consultant, Scott Levenson, said. “There isn’t a tremendous amount of partisan politics in the city at the moment,” Mr. Levenson said. With three years left before the next citywide election, officials are more concerned with getting things done, he said. Mr. Levenson said Mr. Carrion has assumed a “less explosive and confrontational” rhetorical style than Mr. Ferrer, and that has allowed him to work well with City Hall.

While Mr. Bloomberg has drawn attention for his increased national profile since winning re-election, he has also appeared at numerous groundbreakings and ribbon-cuttings across the five boroughs to trumpet the progress and completion of developments that stem from his first term.

Mr. Carrion, who took office with Mr. Bloomberg in 2002, has stood with the mayor against community opposition to plans for the Bronx Terminal Market and a new Yankee Stadium. Yesterday, the borough president appeared to get his reward, as the mayor said Mr. Carrion “deserves an enormous amount of credit” for the projects.