After 15 months of seeing Democratic plans laid waste by an unyielding president, Speaker Nancy Pelosi (D-Calif.) struck back last week with a vengeance.

Pushed into a corner by President Bush’s decision to try to force a vote on the Colombia free-trade agreement without her consent, Pelosi counterpunched, ramming through a change in House rules to block a vote on the pact and transforming a divisive issue for her Caucus into one of the few bargaining chips she’s had to play with since the Democrats gained control of Congress.

The Speaker could barely contain her glee last week as she mentioned her favorite new word — “leverage” — at least 15 times as she effectively took the Colombia agreement as a hostage in negotiations over an array of stimulus proposals Democrats are assembling.

“What happened today is the leverage came back to working people in our country,” she said. “The timetable in Congress is with the working people in our country and not with the president of the United States.”

After a White House meeting with Bush on Wednesday afternoon, Pelosi talked of “leverage” three times in brief remarks, included the word twice in remarks prepared for delivery on the House floor Thursday, and in a post-vote press conference declared Democrats had gained the upper-hand another 10 times.

“We have had conversations that haven’t amounted to much because they had all the leverage and didn’t think they had to do anything. Now the leverage has changed,” Pelosi said of the discussions with Bush.

Her not-so-subtle message to the Republicans and the president: I can play hardball and kill your bills, too.

Pelosi hasn’t been in this position often, because as Democrats point out, Bush hasn’t had much of a legislative agenda beyond keeping the war going. (Pelosi has also blocked Bush’s third major priority this year — retroactive immunity for telecommunications companies as part of an update to the Foreign Intelligence Surveillance Act.)

Although Democrats point to a handful of successes from their first year in office — including a minimum-wage increase and an energy package — they remain frustrated at the president’s killing of bills that would have ended the Iraq War, expanded children’s health insurance and increased spending on domestic programs.

Pelosi made clear that she is open to supporting the Colombia free-trade pact, but only if Bush shows her the money, and she named a laundry list of potential ransom items, including unemployment insurance, infrastructure spending, assistance for workers displaced by trade, aid to states and even aid for the mortgage crisis. All could be part of what would amount to an expensive “Get the Colombia deal out of Jail” card. About the only issue she didn’t mention was an expansion of children’s health insurance, although Democrats privately have brought that up to Republicans as well.

Republicans reacted with outrage, with House Minority Leader John Boehner (Ohio) calling Pelosi’s move “despicable,” “cheating” and “political blackmail.”

“She wants the president to deal with her on her agenda, and we’re not going to move this bill until the president deals with her agenda,” Boehner said. “That is not the way to deal with our trading partners around the world.”

And Boehner accused Pelosi of stringing the Bush administration along. “The reason this bill was sent up here this week was because not one time over these six weeks has the Speaker agreed or made a commitment to the administration that this bill will be considered this year,” Boehner said.

Boehner, the Bush administration and Congressional Republicans said U.S. companies and workers would be harmed because most of Colombia’s goods already enter the United States duty-free, while U.S. goods face stiff tariffs in return. And they point to Colombia’s role as a bulwark of American support and a counterweight to Venezuelan President Hugo Chávez as another reason not to use the agreement as a mere bargaining chip.

“She’s willing to hurt our economy, hurt American workers, hurt our best ally in South America, in some kind of shallow, transparent political maneuver,” said Michael Steel, spokesman for Boehner.

Boehner, for one, didn’t sound much in the mood to negotiate with a legislative gun to his head — he declared the Colombia pact dead — and Republican leaders have strongly resisted calls for additional stimulus packages, arguing that the first one hasn’t had a chance to work yet.

Democrats countered that Republicans are on the defensive as the economy continues to slide. The GOP attacks are “nothing but blanket statements by Republicans who are unable to explain to their voters why they are unwilling and unable to bring relief to millions of Americans,” Pelosi spokesman Nadeam Elshami said. “The Speaker and Democrats are willing to sit down with the administration and Republican leaders to work on an economic plan that will bring growth and a stimulus.”

Meanwhile, as Republicans were in a sour mood, Pelosi was cutting jokes.

“I have to go back to work and use my leverage on a level playing field,” she quipped at the end of the press conference Thursday.

Jennifer Yachnin contributed to this report.