WASHINGTON (Reuters) - President Barack Obama expanded his lead over Republican challenger Mitt Romney to 6 percentage points in the White House race this month as voters became slightly more optimistic about the economy, a Reuters/Ipsos poll showed on Tuesday.

Four months before the November 6 election, Obama leads Romney among registered voters 49 percent to 43 percent. Last month, Obama held a slim 1-point lead over the former Massachusetts governor.

Obama's improved standing was fueled by a rise in optimism about the future, with the number of Americans who think the country is on the wrong track dipping 5 percentage points to 58 percent.

Obama's approval ratings ticked up 1 point to 48 percent and the number of Americans who disapprove of Obama's job performance dropped 3 percentage points to 47 percent.

(Reporting by John Whitesides; Editing by Eric Beech)