WASHINGTON (Reuters) - Republican presidential candidate John McCain runs even with Democratic rival Barack Obama and narrowly leads Hillary Clinton in potential match-ups in November, according to a Reuters/Zogby poll released on Wednesday.

McCain was seen as a better steward of the economy than either Democrat despite their repeated criticism of his economic credentials. He led Obama by 3 points and Clinton by 5 points on the question of who would best manage the economy.

In the Democratic race, Obama widened his national lead over Clinton to 51 percent from 38 percent, up from a 3-point edge in March, in polling taken before a controversy erupted over Obama’s comments about small-town residents.

The two Democrats, battling for the right to face McCain in November’s presidential election, both gained ground on the Arizona senator nationally in the last month although Obama fares slightly better in head-to-head match-ups.

Obama pulled into a statistical tie with McCain at 45 percent after trailing him by 6 points last month. Clinton trails McCain by 5 points, 46 percent to 41 percent, gaining slightly from an 8-point deficit last month.

“Obama still does better than Clinton against McCain, but it’s a very close race either way,” pollster John Zogby said. “Obama and Clinton hurt each other the longer their race drags on, and McCain is getting a free pass.”

Heading into the next Democratic contest in Pennsylvania on Tuesday, Obama has been under heavy fire from Clinton and McCain for saying small-town residents are bitter about the ailing economy and cling to religion, guns and anti-immigrant bigotry in frustration.

The national poll, taken Thursday through Saturday, was nearly completed before the Obama controversy erupted when his April 6 comments at a private San Francisco fundraiser became public on Friday night. The furor’s impact on the Democratic race is unclear.

CYCLICAL RACE

Obama had gained ground on Clinton in the last month after weathering a controversy over inflammatory statements by his pastor, the Rev. Jeremiah Wright, while Clinton came under fire for falsely claiming to have faced sniper fire in Bosnia in 1996.

“Obama rebounded from the Reverend Wright situation and it was Clinton’s turn to get scrutinized,” Zogby said. “Now it’s back to Obama for the small-town comments. This race has been very cyclical.”

The poll found Obama made gains in the last month among at least two key national constituencies that have sustained Clinton’s bid. The Illinois senator led among women, 48 percent to 42 percent, and among whites, 46 percent to 41 percent.

Obama also held big leads among men, blacks, young voters and high-income voters. Clinton, a New York senator, led among the elderly, Hispanics and voters with less than a high-school education.

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Obama has been steadily narrowing the gap on Clinton in Pennsylvania, where her sizable double-digit poll lead had dwindled to single digits in most recent polls.

An Obama win in Pennsylvania could knock Clinton out of the race, while she needs a big victory to make headway in her effort to overtake Obama in the popular vote cast in state contests and pledged delegates to the nominating convention.

With 10 contests remaining, Obama has a nearly unassailable lead in pledged delegates, but neither candidate is likely to gain enough delegates to win without help from nearly 800 Democratic Party officials and insiders who are free to back any candidate.

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The poll also gauged potential head-to-head match-ups if independent Ralph Nader or possible Libertarian candidate Bob Barr, a former congressman, get on the ballot. Nader drew 3 percent and Barr 2 percent in both national match-ups.

McCain fared slightly worse against Obama with Barr and Nader in the race, but their presence did not change his margin over Clinton.

The national survey of 532 likely Democratic primary voters had a margin of error of 4.3 percentage points. The poll of the race between McCain and the two Democratic contenders surveyed 1,049 likely voters with a margin of error of 3.1 percentage points.

(Editing by Mohammad Zargham)