Sen. John Kerry, sharing a stage with President Bush during the first presidential debate Thursday night in Florida, established himself as a credible candidate for president. As amazing as that sounds with only four weeks left in the race, Kerry needed to prove himself and answer questions voters still have about him.

If the name of the game in the debate is expectations, Kerry exceeded his. Bush, prone to platitudes, gave into that temptation early. But the president was able to stay on message, repeating key phrases – mixed messages, speaking clearly, flip-flopper and indecisive – to drive his point home effectively. He was relentless and disciplined, but he also stumbled.

Bush, who’s normally cool on the stump and on the stage, appeared, at times, on the defensive. Kerry, swinging for the fences, was much more aggressive, perhaps realizing he must begin to make up ground on the president. Several recent national polls show the president leading by about 6 points.

On Iraq and securing the country from attack, Kerry and Bush reiterated the arguments they have made throughout the campaign. They covered little new ground, but for the estimated 40 million viewers, many of whom haven’t followed the campaign day to day, the debate offered an excellent introductory into the major themes and differences.

Kerry continued to hammer away on the mistakes he thinks Bush has made both in the run-up to the war and in its prosecution. Bush defended the war in Iraq as an essential part of the war on terror.

Neither man did a good job of laying out future plans for Iraq. They looked backward and argued about today, but an outline for what should happen tomorrow was absent, beyond the consistent themes of “staying the course” and “bringing in more allies.”

Kerry mixed good pieces of information throughout the debate, but failed to follow up on some of the details driving his argument. He let several good opportunities slip by, especially when bringing the war down to the soldier level. Bush hit his key points and stayed on them.

The candidates expressed sharp policy distinctions on North Korea and Iran. With help from moderator Jim Lehrer and by ignoring the rules, viewers got to see a real exchange with significant details that continued into the next several questions.

Character, as nebulous as the idea is, matters because nobody can be sure what the next foreign policy crisis will be. To that end, Bush and Kerry have worked hard to caricature the other’s mettle. Moderator Lehrer prodded the issue with a pointed question directed toward Bush: Does Kerry have character flaws that disqualify him from being president?

Both men, in what appeared to be a genuine moment, acknowledged the knock-down-drag-out nature of a presidential campaign. They were at their likable best.

Going into the debate, improving his likability was a hurdle Kerry had to clear. His aggressive go at the president might have turned some voters off. But the short, direct answers demanded by the debate’s format helped to rein in the senator’s sometimes long-winded soliloquies.

And everyone can be thankful that the debate escaped, for the most part, from the grasp of the Vietnam War, focusing instead on the here and now.

The stakes were high for both men. For Kerry, the debate was an opportunity to close the gap.

Live, interactive and immediate spin was flying through cyberspace even as the candidates moved past the first few questions Thursday night. The Republicans, at DebateFacts.com, and Democrats, at blog sites such as Washingtonmonthly.com and atrios.blogspot.com, offered instant analysis and fact checking.

True believers could find confirmation of the “truth” before the candidates could finish, as the GOP offered up, their “vacillations, defeatism and personal attacks.”

If the past is a clue, the first presidential debate is the most watched, and has provided an opportunity for a candidate to create momentum. Much of any post-debate bounce could depend on the way the debate plays in the media until the two candidates meet again on Oct. 8.

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