* Lead growing over past week
* A tighter race on economic issues
By Alina Selyukh
WASHINGTON, Sept 13 (Reuters) - President Barack Obama widened his lead over Republican challenger Mitt Romney to 7 percentage points in a Reuters/Ipsos poll of likely voters on Thursday, the latest survey to show the Democrat ahead in the run-up to the Nov. 6 election.
The daily online poll asked 990 likely voters over the previous four days which candidate they would pick if the vote took place today, with 48 percent choosing Obama and 41 percent picking Romney.
The gap has been widening since Obama grabbed the lead in the rolling poll on Sept. 7 when he scooped up 46 percent of likely voters to Romney's 44 percent after the Democratic convention.
"What that really means is that Obama is in good shape," said Ipsos pollster Julia Clark, attributing some of Obama's uptick to the slowly improving sentiment toward the direction of the country shown in Wednesday's telephone poll.
Among all 1,231 registered voters surveyed online, Obama led with 45 percent to Romney's 39 percent.
Thursday's online poll also found far more registered voters preferred the incumbent's policies and approach on taxes (41 percent picked Obama, 30 percent Romney), healthcare (44 percent Obama, 28 percent Romney) and Social Security (39 percent Obama, 27 percent Romney).
Asked which of the candidates had a better plan, policy or approach to the war on terrorism, more registered voters again favored Obama: 39 percent to Romney's 25 percent.
Foreign policy moved to the center of the campaign this week after four Americans, including an ambassador, were killed in Libya as protests raged in Benghazi and Cairo in neighboring Egypt against an anti-Islam film made in the United States.
The two candidates ranked closely on the U.S. economy: 36 percent said Obama's approach was better, versus 35 percent for Romney. Obama held a slight lead of 38 percent to Romney's 35 percent on jobs and unemployment, despite poor unemployment figures last Friday.
But 35 percent of registered voters found Romney's policies and plans on the federal deficit were better than Obama's. Thursday's poll showed Obama with 31 percent.
Independents - a key voting bloc - favored neither of the candidate's policies on many issues.
"Neither candidate has established credibility on these issues," Clark said. "Neither candidate is really doing it for these independents."
Asked for whom they would vote for in Thursday's poll, the small pool of independents preferred Romney with 35 percent to Obama's 26 percent, which Clark attributed to their high focus on economic issues.
The precision of Reuters/Ipsos rolling daily online polls is measured using a credibility interval. In this case, the poll has a credibility interval of plus or minus 3.2 percentage points for all respondents. (Editing by Alistair Bell and Peter Cooney)