The head of the Transport Workers Union Local 100, Roger Toussaint, is planning to march across the Brooklyn Bridge and into a Lower Manhattan jail cell today, four months after he led his union’s 34,000 members on an illegal strike.

The move has some observers saying that Mr. Toussaint is seeking to cast himself as a martyr, while supporters yesterday lauded him as a genuine hero to the labor movement.

Mr. Toussaint chose not to appeal a judge’s decision to sentence him to 10 days in jail for violating the state’s Taylor Law, which outlaws strikes by public employees. Instead, the union president is turning himself in with the fanfare of a large rally in Brooklyn. The rally and march are seen as a political gambit to pressure the Metropolitan Transportation Authority to ratify a contract with the transit union and to highlight what several city labor leaders and some Democrats say are unfair provisions of the Taylor Law.

A group of Brooklyn Democrats were at City Hall yesterday to voice their support for Mr. Toussaint, hailing him as a hero and likening his cause to that of the Reverend Martin Luther King Jr. and the Polish leader Lech Walesa.

“African American leaders are especially outraged by the thought that Roger Toussaint could lose his freedom because he had the courage to fight for the dignity of workers and for a better quality of life for workers,” Assemblyman Roger Green said.

Mr. Green, a candidate for Congress in Brooklyn’s 10th District, called for city workers to stand in solidarity with Mr. Toussaint by participating in a 10-day vigil outside the Bernard B. Kerik Complex, the jailhouse at 125 White Street nicknamed The Tombs, where Mr. Toussaint will serve his sentence. Labor leaders from around the city, as well as the Reverend Al Sharpton, are expected to attend today’s rally.

Another assemblyman of Brooklyn, Nick Perry, said he would introduce legislation to “repeal some of the draconian measures of the Taylor Law,” which was enacted in 1967 after a transit strike the previous year. Mr. Perry said it was “an overreaction.”

Mr. Toussaint’s stint in jail comes as the transit union’s membership, in a second vote tallied last week, overwhelmingly approved a contract it had narrowly rejected in January. The contract dispute is now in binding arbitration, but Mr. Toussaint wants the MTA to ratify the agreement he negotiated in December after the three-day strike. The MTA’s board meets Wednesday, but the authority has dismissed the union’s revote as an “empty gesture,” saying the offer was off the table after the initial ballot.

In addition to sentencing Mr. Toussaint to jail and fining him $1,000, a state Supreme Court judge, Theodore Jones, also fined the union $2.5 million and suspended its automatic collection of dues from members.

Other local labor leaders have spoken out against the Taylor Law in recent weeks, including the head of the United Federation of Teachers, Randi Weingarten, who criticized the law for being “stacked against workers.” She said it contains harsh penalties against employees but none against management.

A professor of labor law at New York Law School, Arthur Leonard, expressed skepticism about Mr. Perry’s proposals and said Mr. Toussaint’s tactics were likely a political calculation made with his membership in mind. “We have to remember union leaders are elected,” Mr. Leonard said.

While union foes of Mr. Toussaint support the call to repeal the Taylor Law, his decision to make such a public march into jail drew criticism from a TWU vice president who is an opponent of the president, Bill Pelletier. “It’s not about him, it’s about the Taylor Law,” Mr. Pelletier said. “He’s trying to take a bad situation and turn it around for his own benefit.”

Mr. Toussaint was unavailable for comment yesterday. The union would not offer an official response to criticism of the leadership, but a source close to Mr. Toussaint said, “Roger didn’t ask to go to jail, but he knew the consequences of a strike, and he’s more than willing to serve the time.”