After a deluge of campaign speeches and hostile television ads, President Bush and challenger John Kerry got their chance to face each other directly Thursday night before an audience of tens of millions of voters in a high-stakes debate about terrorism, the Iraq war and the bloody aftermath.

The 90-minute encounter was particularly crucial for Kerry, trailing slightly in the polls and struggling for momentum less than five weeks before the election. The Democratic candidate faced the challenge of presenting himself as a credible commander in chief after a torrent of Republican criticism that he was prone to changing his positions.

Bush was expected to confront questions about leading the nation into war on the still-unproven premise that Iraq had weapons of mass destruction. He also has faced accusations that he lacked a strategy to deal with the violence and chaos that have left more than 1,000 Americans dead and that the Iraq war has diverted U.S. attention from al-Qaida and other terrorists.

With a record of four years in office to defend, Bush had a debate strategy of being optimistic about Iraq but acknowledging that times were tough. His stance is that Americans know he is a decisive leader even if they don't always agree with his decisions and that Kerry has taken conflicting positions on Iraq and can't be trusted to lead the nation. (...)

Ahead in the polls, Bush could afford to settle for a debate draw while Kerry needed something to break the status quo. Some Democrats saw the debates as the last chance for a Kerry breakout.

Thursday night's meeting at the University of Miami was the first of three Bush-Kerry debates over a two-week period. Neither side was underestimating its importance with a TV audience of 30 million to 40 million expected. Almost a third of people surveyed say the debates will be a deciding factor in how they vote.

The first debate drew the nation's attention to hurricane-battered Florida and its political importance. Florida swung the presidency to Bush in the disputed 2000 election and could determine whether he wins re-election.

The debates were staged under a rigid set of rules negotiated by the candidates' representatives to limit spontaneity and opportunities for back-and-forth exchanges.