* Obama's approval rating up slightly to 50 pct
* Edges Romney on healthcare, economy, foreign policy
* Independents warming to the Democrat (Adds background, details)
By Deborah Charles
WASHINGTON, May 8 (Reuters) - President Barack Obama extended his lead over Republican challenger Mitt Romney to 7 percentage points because of increased support from independent voters and some optimism over the U.S. economy, a Reuters/Ipsos poll showed on Tuesday.
With six months to go before Election Day on Nov. 6, Obama was backed by 49 percent of registered voters in the telephone poll, compared to 42 percent who supported Romney. In April, the poll showed Obama leading Romney 47 percent to 43 percent.
The numbers suggest Romney's general election campaign has not yet taken off, although he has effectively clinched the Republican nomination in recent weeks when Rick Santorum and Newt Gingrich dropped out of the race.
Obama's overall approval rating among the 1,131 adults surveyed was 50 percent, up 1 point from last month as the anniversary of the killing of Osama bin Laden gave Obama a chance to tout his national security credentials and stage a high-profile visit to Afghanistan.
Forty-seven percent of people in the poll disapproved of how Obama handles his presidency.
"The economy continues to chug along. Presidential ratings are correlated fairly closely with economic optimism and when the public sees things like unemployment going down and other signs of economic recovery, they are more inclined towards voting for the status quo - which in this case is to keep the incumbent in office," said Ipsos pollster Julia Clark.
The U.S. jobless rate fell to 8.1 percent in April, the lowest since Obama took office in January 2009, although employers cut back on hiring as the economy struggles to pick up growth.
INDEPENDENTS HOLD POWER
Independents swung behind Obama. Forty eight percent approved and 40 percent disapproved of his performance in May compared to 37 percent who approved and 57 percent who disapproved in April.
"Independents obviously are going to be critical in this election," said Clark. "That independent approval jump is absolutely significant. It contributes to his jump in approval month on month. We're talking increments here, but where Obama is right now, the increments matter a lot."
The poll, conducted from May 3-7, showed voters from the two parties are falling in behind their candidates, which makes the independent vote more important, Clark said.
"In the broader picture, this month Obama does really appear to be making that slow but steady progress he will need to continue to make to seal the deal," said Clark.
The poll showed voters think Obama is just slightly stronger than Romney, a former business executive who has touted his economic experience during the campaign, on the issues of jobs and the economy. When asked which of the two was stronger on the topic, 45 percent of registered voters surveyed picked Obama while 43 percent chose Romney.
Among the 959 registered voters surveyed, a majority said Obama was stronger than Romney on healthcare, Afghanistan and the global fight against terror. Romney had a 1-point advantage over Obama on immigration.
The poll was conducted just after Obama made a surprise trip to Afghanistan to mark the first anniversary of the killing of bin Laden. While in Afghanistan, Obama signed a strategic pact with Kabul and told Americans the war was winding down.
Romney, who has criticized Obama's handling of Afghanistan and for setting a timeline for a troop withdrawal, accused the president of politicizing bin Laden's death.
But the poll showed that 51 percent of registered voters thought Obama was stronger on Afghanistan and on terrorism while 28 percent said Romney had a stronger position on Afghanistan.
The Reuters/Ipsos survey, conducted over landlines and cell phones, is considered accurate within 2.9 percentage points for the total sample. Among registered voters it has a margin of error of 3.2 percentage points. (To see full text of poll click on http://www.ipsos-na.com/news-polls/pressrelease.aspx?id=5621) (For graphic click on http://link.reuters.com/kub28s) (For complete coverage of the U.S. presidential election please click on ) (Reporting by Deborah Charles. Editing by Alister Bell and Christopher Wilson)