WASHINGTON — Desperate to avoid another market-crushing defeat, House leaders won key converts Thursday to the $700 billion financial industry bailout on the eve of a make-or-break second vote.

President Bush and congressional leaders lobbied furiously for the dozen or so supporters they'd need to reverse Monday's stunning setback and approve a massive rescue plan designed to stave off national economic disaster.

Anything but reassured, investors sent the Dow Jones industrials plunging another 348 points, suggesting Wall Street is expecting tougher economic times even if the measure is rushed into law. The Federal Reserve reported record emergency lending to banks and investment firms, fresh evidence of the credit troubles squeezing the country.

"A lot of people are watching," Bush pointed out — as if lawmakers needed reminding — and he argued from the White House that the huge rescue measure was the best chance to calm unnerved financial markets and ease the credit crunch. He was calling dozens of lawmakers, a spokesman said.

Democratic and Republican leaders worked over wayward colleagues wherever they could find them.

Rep. Steny Hoyer, the second-ranking House Democrat, said there was a "good prospect" of approving the measure but stopped short of predicting passage — or even promising a vote. Nonetheless, the vote was expected on Friday. "I'm going to be pretty confident that we have sufficient votes to pass this before we put it on the floor," Hoyer said.

The top Republican vote-counter, Rep. Roy Blunt of Missouri, did predict the measure would be approved.

Minds were changing in both parties in favor of the much-maligned measure, which would let the government spend billions of dollars to buy bad mortgage-related securities and other devalued assets from troubled financial institutions. If the plan works, advocates say, that would allow frozen credit to begin flowing again and prevent a serious recession.

GOP Rep. Ileana Ros-Lehtinen of Florida, said she was switching her "no" vote to a "yes" after the Senate added some $110 million in tax breaks and other sweeteners before approving the measure Wednesday night.

"Monday what we had was a bailout for Wall Street firms and not much relief for taxpayers and hard-hit families. Now we have an economic rescue package," Ros-Lehtinen told The Associated Press.

Rep. Zach Wamp of Tennessee, another of the 133 House Republicans who joined 95 Democrats Monday to reject the measure, also announced he was now onboard, even though "I hate it." He told the AP, "Inaction to me is a greater danger to our country than this bill."