April 28 (Bloomberg) -- Hillary Clinton does better than Democratic presidential rival Barack Obama when matched against Republican John McCain, according to the latest Associated Press- Ipsos poll.

Clinton leads McCain 50 percent to 41 percent while Obama is ahead 46 percent to 44 percent, within the margin of error, according to the poll taken after Clinton's Pennsylvania primary victory. Earlier this month, the poll showed Clinton leading 48 percent to 45 percent over McCain, and Obama and the presumptive Republican nominee were tied at 45 percent.

Senator Clinton of New York has been arguing that she has a better chance of beating McCain than Senator Obama of Illinois, who leads in the delegate race for the Democratic nomination. The Democrats' uncommitted superdelegates, drawn from party officeholders and leaders, are in position to determine who gets the nomination.

Among Democratic voters, Obama leads Clinton 46 percent to 43 percent, according to the AP-Ipsos poll taken April 23-27. That is unchanged from the previous survey about two weeks earlier.

The survey also found that 44 percent of Democrats think the protracted battle for the nomination will make it harder for Democrats to win in November, while 30 percent don't think it will have an impact and 18 percent believe it will help Democrats win the general election.

The telephone poll surveyed 1,001 adults nationwide. The margin of error among Democratic and likely Democratic voters was plus or minus 4.6 percentage points and among Republicans and likely Republican voters plus or minus 5.3 percentage points.

The matchups against Senator McCain of Arizona are closer in a Gallup poll released today. Clinton leads McCain 47 percent to 44 percent while Obama runs even with him at 45 percent, the poll found.

That is within the margin of error in the telephone survey of 4,346 national registered voters taken April 23-27.

A Gallup telephone survey of 1,230 Democratic and Democratic-leaning voters taken April 25-27 has Obama leading Clinton 47 percent to 46 percent, also within the margin of error.

To contact the reporter on this story: Julianna Goldman in Washington at jgoldman6@bloomberg.net

Last Updated: April 28, 2008 17:41 EDT