Defying the White House, Nancy Pelosi said Wednesday the House will change its rules to avoid a required vote this year on a hotly disputed free-trade agreement with Colombia.

Pelosi said she will bring a procedural change to the House floor on Thursday that would remove the timetable under which Congress would have had to take up trade bills within 90 legislative days after they are received from the White House.

"The president took action" in submitting the Colombia free trade agreement to Congress on Tuesday, she said. "I will take mine tomorrow." Pelosi said that Bush called her Monday to tell her he was sending the agreement to Congress.

The White House has aggressively pushed Congress to approve the trade deal with Colombia, arguing that helping a key ally in South America is in the political and security interests of the United States.

House Republican leader John Boehner, R-Ohio, said in a statement that Pelosi's proposed rule change "would be cheating." He asked what nation "would conclude a treaty with the United States knowing that Congress can change the rules of the game after it is negotiated?"

But most Democrats, backed by organized labor and some human rights groups, are against it. They have cited violence against union organizers in Colombia and have also made clear they won't consider further free trade agreements until legislation is passed to expand current programs to help American workers displaced by foreign trade.

"Our focus on Colombia is the continuing violence against trade unionists," said Bill Samuel, the AFL-CIO's legislative director. He said he thought Pelosi's action would effectively stop any action on the agreement this year.`

Pelosi, at a news conference, said that if legislation approving the trade deal were taken up now, it would be defeated, "and what message would that send" to the Colombian people?

She denied that the rule change doomed action on the agreement this year, saying that "depends on the good faith in which we conduct these negotiations." The administration has been talking to Democrats about ways to help American workers. The House last year passed legislation to expand the Trade Adjustment Assistance program that provides financial aid and training to people who lose jobs as a result of trade, but the White House threatened a presidential veto and the Senate never took it up.

Pelosi insisted that the House's right to determine its own procedures overrides any requirements that Congress take up a measure within a prescribed time period.

She said she is interested in taking up the agreement in an atmosphere that is "as unemotional as possible," but "that is not possible if the president of the United States is going to usurp the discretion of the speaker of the House to bring" legislation to the floor.

The administration contends that the Colombian government has made significant strides in reducing violence. Secretary of State Condoleezza Rice and Treasury Secretary Henry Paulson, in a letter to Pelosi last week, said the agreement "will send a clear message of support to a strong democratic ally, particularly given the continuing assault on the government of Colombia by narco-terrorists and the recent provocative actions by an increasingly aggressive Venezuela."

They also pointed out that the agreement would help American exporters. While Colombia already enjoys duty-free status on almost all its exports to the United States, the agreement would reduce and eventually eliminate tariffs on U.S. shipments to Colombia.