WASHINGTON, USA (AP) – Barack Obama bolstered his case that he’s ready to be chief executive with a calmly assured response to the economic crisis and a solid debate performance.

Is America convinced? Presidential rival John McCain argued yesterday – and is certain to repeat in the five weeks ’till election day – that the young senator lacks the experience and judgement to be president.

“A vote for Senator Obama will leave this country at risk,” McCain told a rally in Columbus, Ohio, ratcheting up the criticism in a speech that acknowledged his likeliest path to the White House was casting his Democratic rival as unacceptable. McCain said the choice voters face is: “Country first or Obama first?”

Obama countered that McCain is the one who “doesn’t get it” and likened his GOP rival to “a bet we can’t afford”. Aligning McCain with the unpopular President Bush on the economy, Obama said: “The greatest risk in this election is to repeat the same mistakes of the past. We can’t take a chance on the same losing game.”

McCain lags in recent polls that also show Obama gaining some ground in overcoming his candidacy’s biggest hurdle – convincing skeptics who have trouble seeing the 47-year-old freshman senator, vying to be the first black president, in the White House.

Still, the political environment remains unpredictable, underscored by stocks plunging dramatically yesterday amid the House’s rejection of a $700-billion financial industry bailout.

That raised the question anew of whether voters will be willing to take a chance on the untested Obama and his message of change, or whether they will opt for the more experienced McCain, who, despite public antipathy toward the GOP, his acknowledgement that economics is not his strongest issue and his uneven reaction to the crisis. Conversely, it’s possible that hunger for economic change may outweigh voters’ concerns about the Democrat and the public may blame Republicans.

Within an hour of the House defeating the bill, Obama sought to calm fears by saying: “I’m confident we’re going to get there, but it’s going to be rocky,” McCain said a statement from senior policy adviser Doug Holtz-Eakin that blamed Obama and Democrats for the legislation’s failure – even though more Republicans than Democrats voted against it.

Unconventional in many ways, this campaign has become a referendum on Obama’s readiness to serve rather than a judgment on McCain after eight years of GOP rule under Bush. Thus, Obama is trying to meet the qualification threshold as McCain seeks to undercut him.

In an election year that favours Democrats, Obama has been unable to sustain a lead of a couple of percentage points in key electoral-rich states such as Ohio, Florida and Pennsylvania.

Race is certainly a factor. A recent AP-Yahoo News poll suggested that Obama’s support would be as much as six percentage points higher if there were no white racial prejudice.

However, the poll also showed that doubts about Obama’s competency loom even larger than race. More than a quarter of all Democrats expressed doubt that Obama can bring about the change they want, and they are likely to vote against him because of that. And, three in 10 of those Democrats who don’t trust Obama’s change-making credentials say they plan to vote for McCain.

Thus, Obama has sought to allay such concerns through words and actions.

Amid wrangling over the bailout last week, Obama kept his distance from Washington while making it known that he was checking with key players. He balked when McCain put most campaign activities on hold, called for a postponement of the first debate and returned to Capitol Hill, saying presidents need to “deal with more than one thing at once”.

After Bush summoned him to Washington, Obama was credited as the candidate who took charge inside the Cabinet Room. He suggested McCain’s return had muddied negotiations. “It’s important not to inject presidential politics into this,” Obama said afterward and added: “It’s amazing what you can get done when you’re not looking to try to get credit for it.”

A day later, Obama held his own in a debate on McCain’s forte – foreign policy. The Democrat displayed a comfortable understanding of the issues and took the Republican to task over Iraq, repeatedly saying: “You were wrong.”

McCain, for his part, faces dwindling options to derail Obama.

The Republican has two more debates with Obama – a town hall-style forum in which McCain should thrive and one focused on the economy in which Obama goes in with the edge. Analysts in both parties say it’s difficult to see how McCain changes the campaign trajectory without a major Obama gaffe or an outside event breaking in the Republican’s favour.

He assailed Obama over his response to the economic crisis, calling the Democrat’s hesitancy to return to Washington a failure of leadership. He also questioned Obama’s honesty on taxes, saying: “We need a president who will always tell the American people the truth.”

This week, the focus will be on a debate between vice-presidential nominees Joe Biden and Sarah Palin.

Biden, a veteran senator, is an experienced debater though prone to verbal missteps. Palin has come across poorly in the few interviews she’s granted, and even conservative commentators who once praised her selection now say she’s not ready to be president should the need arise.