US election race heats up
Washington - US President Barack Obama and presumptive Republican nominee Mitt Romney are fully engaged in an intensifying White House race in the lead up to a general election on November 6.
Recent spats over the economy, women voters and taxes offer hints on Democrat Obama's strategy and underscore the threats he faces in his bid for a second term.
Some key Obama goals and liabilities as the race heats up.
It is never too late to make a first impression. But the Obama camp wants to stop Romney reintroducing himself to voters after the fierce Republican primary season.
Obama paints multi-millionaire Romney as out of touch with the struggles of the middle class and promises an economy where everyone has "a fair shot."
His own rules
So, Obama and Vice President Joe Biden released their tax returns on Friday, and goaded Romney to release his, believing they will show he took advantage of investment income rules to secure a low tax rate.
"Governor Romney may try once again to play by his own set of rules, but Americans will hold him accountable for trying to hide his record," said Obama campaign manager Jim Messina.
Obama leads Romney in most polls and the economy is coming off a spurt of momentum which created a million jobs in five months.
But the recovery is vulnerable to outside shocks - like any dreaded worsening of the European debt crisis.
Growing White House confidence has also been tempered in recent days.
Jobs growth slowed to only 120 000 positions last month. Unemployment remains at 8.2%. And new claims for unemployment benefit rose last week for the second week in a row.
With Congress deadlocked, Obama can do little to stimulate growth so has to wait and hope things improve, knowing the economy could condemn him to a one-term presidency.
His strategy is to try to convince voters that if Republicans win in November, things would be worse.
"The economy is getting stronger. The recovery is accelerating and the last thing we can afford to do right now is to go back to the same, worn-out, tired, uninspired, don't-work policies that got us into this mess," Obama said.
US elections are often won on the shifting centre ground between committed Democratic and Republican voters.
A USA Today poll showed Obama beating Romney 48% to 40% among independents in battleground states - but the crucial number for each campaign is 12% - the number of uncommitted voters who were undecided.
Obama must thwart any bid by Romney to move to the centre and prevent the Republican repairing poor ratings among vital voting blocs of Hispanics and women voters.
Raise millions of dollars
Romney and Obama will criss-cross America to pile up campaign funds.
The president mixes clutches of fundraisers into trips on official business, allowing him to raise several million dollars on a single day.
One event in upscale Palm Beach Gardens, Florida last Tuesday drew 60 people, who each paid $10 000 to attend.
Obama had raised $157m for his reelection effort by the end of February and spent $75m, according to the Centre for Responsive Politics, which tracks campaign spending.
Romney had raised $75m, and spent $66m on his primary campaign, which he effectively wrapped up last week.
But he will likely benefit from a torrent of spending by corporations and wealthy individuals who can give unlimited cash to Super PAC committees that support him, thanks to a controversial 2010 Supreme Court ruling.
Trigger a crisis
A sitting president is hugely vulnerable to events beyond his control. A swiftly developing foreign crisis for instance, mishandled by the White House could have an immediate electoral impact.
Any Israeli strike on Iran's nuclear programme for instance, could trigger a geopolitical crisis, send oil and gasoline prices soaring and hammer the US economy.
Or a sudden deterioration in the war in Afghanistan could puncture the president's claim to a solid record as US commander-in-chief.
There is also another big intangible at home: the Supreme Court is expected in June to reveal whether it will throw out Obama's health care reform law.
If it does, Obama's personal and presidential prestige would be battered, and there would likely be an explosive impact on the election campaign.