Obama tightens grip on chance of second term

To overtake Mr Obama, Republican Mitt Romney would need to quickly gain the upper hand in nearly all of the nine states where he and Mr Obama are competing the hardest.

Polls show the President with a steady lead in many of them as Mr Romney looks to shift the dynamics of the race, starting with their first debate on Wednesday in Denver.

If the election were held today, an Associated Press analysis shows Mr Obama would win at least 271 electoral votes, with likely victories in crucial Ohio and Iowa, along with 19 other states and the District of Columbia. Mr Romney would win 23 states for a total of 206.

To remove the Democratic incumbent, Mr Romney would need to take up-for-grabs Florida, Colorado, Nevada, North Carolina, New Hampshire and Virginia, which would put him at 267 votes, and upend Mr Obama in Ohio or Iowa.

US presidents are elected not by national vote but in state-by-state contests. Each state gets one electoral vote for each of its representatives in the House and Senate. There are 538 votes in the Electoral College, and a candidate must have at least 270 to win. Except for Maine and Nebraska, states award all their electoral votes to the candidate who wins the state.

In the final weeks before the November 6 vote, Mr Obama is enjoying a burst of momentum and has benefited from growing optimism about the economy as well as a series of Romney stumbles. Most notably, a secret video showing the Republican nominee telling a group of wealthy donors that 47 per cent of Americans pay no federal income taxes and consider themselves victims dependent on the government.

Ohio’s shifting landscape illustrates Mr Romney’s troubles. The president has benefited from an improving economic situation in the state and the car industry bailout and General Motors plant expansions in eastern Ohio is helping to maintain his lead.