WASHINGTON - Voter approval of President Barack Obama is on the rise, in sync with a perked up U.S. economy and growing turmoil among Republicans battling for the nomination to challenge him in November.

Polls show Obama in a far better position than at any time since he ordered the Special Forces operation that killed al-Qaida leader Osama bin Laden last May. But the president's approval remains closely tied to events over which he has little control.

The economy, while showing signs of accelerated improvement after a painfully slow recovery from the 2007-2009 Great Recession, remains fragile and could easily be knocked off course by further financial tumult in Europe, a spike in oil prices - especially if Israel bombs Iranian nuclear facilities - and a reversal in the downward trend in the U.S. unemployment rate.

The Gallup polling organization shows Obama has pulled out of a steep downward slew that took him into dangerously low territory, with just 38 per cent approval and 55 per cent disapproval late last August. The organization's latest daily tracking poll showed the president with equal approval and disapproval ratings of 45 per cent.

A New York Times/CBS poll released on Tuesday puts him in an even better place, with 50 per cent approval.

Obama seems certain to benefit from a deal that was emerging Wednesday on Congress to extend a payroll tax cut and extra jobless benefits through 2012. The pact came together after House Republicans, in a sign that they are not seeking a confrontation with the president, conceded that the roughly $100 billion payroll tax cut would not have to be paid for with spending cuts. A bipartisan deal would mark a clear victory for Obama, who made the payroll tax cut a keystone of his largely ignored jobs creation plan in September.

Still unknown, however, is how voters will react when the fractious Republican primary fight ends with the nomination of a candidate at the party's national convention in late August.

Obama doesn't appear to be as strong in the so-called swing states - those that shift between support for Democrats and Republicans from election to election - as he was when he easily defeated Sen. John McCain in the 2008 presidential vote, which is a series of state-by-state contests.

That said, a Quinnipiac University poll released Wednesday showed voters in swing-state Ohio slightly favoured Obama by 46 per cent to 44 per cent (a statistical tie) over former Massachusetts Gov. Mitt Romney. He holds a clear 47-41 per cent margin over former Pennsylvania Sen. Rick Santorum. Romney and Santorum are locked in a battle for first place in the Republican race after Santorum's sweep last week of caucuses in Colorado, Minnesota and Missouri.

A poll by the Pew Research Center for the People & the Press gives Obama a 10-point margin when measured against either Romney or Santorum. The Times/CBS survey gives Obama a six-point, 48-42 per cent advantage over Romney and seven points over Santorum, 49-41.

The Times/CBS poll shows Romney suffering among key independent voters, who a month ago favoured him over Obama by 46 per cent to 39 per cent. That advantage has been reversed, with 49 per cent now in the Obama column compared with 38 per cent for Romney.

That may be a reflection of the extraordinarily negative Romney campaign, particularly TV advertising attacks in Florida against former speaker of the House of Representatives Newt Gingrich. Gingrich spent a brief period at the top of the Republican field after easily defeating Romney in South Carolina. He has fallen out of contention, however, since he was throttled by Romney in Florida 10 days later.

The U.S. economy has proven to be Obama's curse. The recession that began under his predecessor George W. Bush and the near collapse of the U.S. financial system in the last months of the Bush presidency ravaged the nation with dramatic job losses and a steep decline in output. Unemployment still stands at 8.3 per cent and the economic growth is not sufficient to take much of a bite out of the jobless number.

And Obama's poll numbers on the economy show his precariousness with voters. The Times/CBS poll found that 50 per cent of voters disapproved of the president's handling of the economy, while 44 per cent approved, even with things getting better. That is only four percentage points better than it was a month ago.

Obama is trying to make the best of his rise in the polls and the accompanying signs of a better economy as he makes a three-state swing this week through Wisconsin, California and Seattle.

After a stop that focused on U.S. manufacturing in Wisconsin on Wednesday, Obama is holding eight re-election fundraisers in the Los Angeles area, San Francisco and Seattle.