Liberal Party Endorses Catsimatidis

John A. Catsimatidis, the billionaire businessman and Gristedes supermarket owner running for mayor of New York City, picked up the endorsement of an obscure but potentially influential political group on Tuesday, adding another wrinkle to the Republican primary.

The Liberal Party, a group that once helped play kingmaker for Rudolph W. Giuliani in his runs for mayor, but has fallen on tough times of late, said it would support Mr. Catsimatidis and list him on its ballot line in the November general election. assuming, that is, the party can acquire that ballot line, which would first require a petition drive.

If the line does come through â€" and Mr. Catsimatidis’s $3 billion fortune could go a long way toward helping the party achieve that goal â€" it would allow the supermarket magnate to continue being a thorn in the side of his more establishment Republican rival, Joseph J. Lhota, a former deputy mayor in the Giuliani administration, should Mr. Lhota win the Republican nomination.

Currently, Mr. Catsimatidis is challenging Mr. Lhota in the Republican primary, and he lags behind: one recent poll put him in third place, behind another long-shot candidate, George McDonald, the president of the Doe Fund, a homeless services group.

But the prospect of Mr. Catsimatidis’s persevering past the September primary (“I’m committed to running,” he said at a news conference on Tuesday) will certainly irk Mr. Lhota’s camp, which remains wary of the unlimited war chest that Mr. Catsimatidis, who has opted out of the city’s voluntary public financing program, could bring to bear in the race.

Moments after Mr. Catsimatidis announced his Liberal Party support, Mr. Lhota’s team said Representative Peter King, an influential Republican House member from Long Island, had endorsed Mr. Lhota for mayor.

Mr. Catsimatidis appeared to be enjoying himself at his announcement event, outside an entrance to the subway station at City Hall. “Today is a game changer,” he said of the Liberal Party’s endorsement, saying it would create a fusion ticket for “pro-business New Yorkers and the pro-people New Yorkers â€" that’s what I’m all about.”

“We’re going to have all the people voting for us!” Mr. Catsimatidis said.

He was asked about the large sums he has contributed to the city’s Republican Party committees, which some critics have labeled a de facto way of buying the party’s support.

“I’m going to contribute more!” Mr. Catsimatidis said. “I’m giving far less money than Bloomberg gave.” (Mayor Michael R. Bloomberg also generously donated to the Republican committees when he ran for mayor on the G.O.P. line.)

Tom F. Allon, another Republican hopeful, had previously received the Liberal Party endorsement, but he abandoned his mayoral bid in March. The Liberal Party did not have a ballot line in the 2009 New York City general election. In 2001, Alan Hevesi ran for mayor with the Liberal Party’s endorsement; he received less than 1 percent of the total votes cast. The party endorsed Mr. Bloomberg in 2005.

Martin I. Hassner, the executive director of the Liberal Party, delivered a stirring endorsement of Mr. Catsimatidis, leaning over his podium and speaking with an orator’s cadence.

“This is a force of nature,” Mr. Hassner said of Mr. Catsimatidis. “Nobody like him around.” He said the candidate had the “yearning necessary” to win the race, and called him “a very uncommon, common man.”

“By the way, he’s not perfect,” Mr. Hassner added. “But he’ll be a mayor of the people.”