After a lackluster debate, John McCain now has less than four weeks to turn the race for the White House around, as observers on Wednesday began to wonder aloud whether the Republican who once dubbed himself the comeback kid can win.

One day after McCain faced off in the second of three debates against Barack Obama, political observers said the exchange failed to up-end the front-runner status of his Democratic rival, as the contest ticks down to the November 4 vote.

“Despite John McCain's best efforts, the Arizona senator didn't knock Mr Obama from his cool evasion or even do much to rebut the Democrat's talking points," the conservative Wall Street Journal wrote the morning after the debate.

"This isn't enough to change the dynamics of the race."

Snap polls by US television networks awarded the debate - - the second of a trio of presidential clashes -- to Obama.

Democrats now are optimistic that -- with two of three rhetorical contests over and both won by Obama according to opinion polls -- the Illinois senator is an increasingly good bet to clinch the November 4 election.

"The race is over,” crowed Howard Wolfson, a former spokesman for Senator Hillary Clinton, one of several Democratic rivals vanquished by Obama en route to the sealing the nomination.

Longtime Washington pundit Roger Simon pronounced neither McCain nor Obama the winner, saying that, from his vantage point, both failed in "delivering a knockoutpunch."

"The trouble for John McCain, however, is that he needed one," Xvrote Simon, a writer for The Politico daily newspaper.