WASHINGTON — President Bush’s decision to send the Colombia free trade agreement to Congress yesterday exacerbates a political quandary for Senator Clinton, whose opposition to the deal has been undermined in recent days by news that her former chief strategist plotted for its passage. Mrs. Clinton quickly put out a statement criticizing the president and highlighting her longstanding position against the agreement, which was negotiated in 2006.

The White House move comes a day after the former first lady replaced her chief strategist, Mark Penn, who embarrassed Mrs. Clinton’s presidential campaign by meeting last week with the Colombians to help them navigate the deal through Congress.

Mr. Penn and his public relations firm, Burston-Marsteller, had been retained by Colombia to advocate for the treaty. After Mr. Penn apologized for the meeting on Friday, Colombia fired him and his firm, saying they had disrespected the country.

For Mrs. Clinton, the flap means she will have to redouble her efforts to hold the support of blue-collar Democrats in Pennsylvania, for whom trade has emerged as a major issue amid a slowing economy. Polls have shown a tightening race between Mrs. Clinton and Senator Obama ahead of the April 22 primary in a state where the New York senator once led by more than 20 points. Under the president’s authority to “fast-track” trade legislation, Congress has 90 working days to ratify or reject the Colombia treaty. With scheduled recesses included, lawmakers face a deadline in the last week of September, which could force a hotly debated vote in the middle of the general election campaign, as well as campaigns for candidates in dozens of House and Senate races.

Appearing at the White House, Mr. Bush noted that the agreement involved more than 400 “consultations and meetings and phone calls” with lawmakers over 16 months, and he said it could not wait any longer. “While we’ll continue to work closely with Congress, the need for this agreement is too urgent — the stakes for our national security are too high — to allow this year to end without a vote,” the president said.

Praising Colombia’s President Uribe as a “strong and courageous leader,” Mr. Bush said ratification of the treaty would boost the Latin American’s nation’s efforts to combat terrorism. He pointed to a decrease in kidnappings, terrorist attacks, and murders in Colombia since 2002. “If Congress fails to approve this agreement, it would not only abandon a brave ally, it would send a signal throughout the region that America cannot be counted on to support its friends,” the president said.

While not unexpected, Mr. Bush’s decision to send the deal to Congress with a time clock infuriated Democratic leaders who say they cannot muster sufficient support for the deal without a side agreement on aid for American workers negatively affected by free trade or assurances that Colombia will crack down on attacks on labor organizers.

“As I have said consistently for several months, I oppose signing any trade deal with Colombia while violence against trade unionists continues and the perpetrators are not brought to justice,” Mrs. Clinton said in her statement. “The United States should be pursuing trade agreements that promote human rights and worker rights, not overlook egregious abuses.”

Both Mrs. Clinton and Mr. Obama, who also opposes the Colombia agreement, have stepped up their criticism of free trade pacts as they have campaigned in working-class communities, where treaties such as NAFTA and CAFTA are blamed for pushing jobs overseas. The presumptive Republican nominee, Senator McCain, supports the agreement.

Labor unions are among the groups most critical of the Colombia deal.

The president of the Teamsters, James Hoffa, reiterated in an interview yesterday his dissatisfaction with Mr. Penn’s demotion over his meeting with Colombian officials, saying Mrs. Clinton should sever all ties to the strategist. Told of Mrs. Clinton’s statement emphasizing her opposition to the treaty, Mr. Hoffa replied: “That’s progress.” The Teamsters have endorsed Mr. Obama.

The House speaker, Rep. Nancy Pelosi, and the chairman of the Ways and Means Committee, Rep. Charles Rangel, who helped shepherd a trade deal with Peru through Congress last year, issued a joint statement calling the president’s decision “counterproductive” and saying it jeopardized prospects for the treaty’s passage. “Under present circumstances, we cannot support the U.S.-Colombia Free Trade Agreement,” Mrs. Pelosi and Mr. Rangel said.

The Senate majority leader, Harry Reid, delivered a harsher rebuke, suggesting Mr. Bush was confusing a trade agreement with a “foreign aid package.”

While the U.S. trade representative, Susan Schwab, said the prospects for passage were “good,” both allies and critics of the president’s trade policy said the Bush administration ran the risk that Congress would vote down a trade agreement for the first time in American history.

“We’re sort of in uncharted territory here,” said Todd Tucker, research director for Public Citizen’s Global Trade Watch, which opposes the deal.

A Democrat of New York who broadly supports the Colombia deal, Rep. Gregory Meeks of Queens, said he urged the White House to hold off on sending the agreement to Congress but was rebuffed. “Generally these deals are worked out before he drops them. This deal has not been worked out,” he said in an interview.

Mr. Meeks said the treaty could bring jobs to New York but that he would push for expanded “trade adjustment assistance” to help American workers hurt by the deal.