By John Whitesides

WASHINGTON (Reuters) - Republican Pat Toomey has
opened a 10-point lead over Democrat Joe Sestak among likely
voters in a critical U.S. Senate race in Pennsylvania dominated
by economic worries, according to a Reuters/Ipsos poll released
Tuesday.

Toomey, a conservative former congressman, leads Sestak, a
former admiral elected to Congress in 2006, by 47 percent to 37
percent barely two months before the Nov. 2 election to replace
Democrat Arlen Specter.

Toomey's lead was smaller, 40 percent to 37 percent, among
a larger pool of registered voters.

Sestak's troubles in Pennsylvania are another warning sign for
Democrats ahead of the congressional elections in which they face
potentially big losses in the Senate and the possible loss of
their majority in the House of Representatives.

Pennsylvania's high-profile Senate race is one of more than a
dozen contests that could determine whether Republicans gain the
10 Senate seats they need to regain control of the Senate and slam
the brakes on President Barack Obama's legislative agenda.

Voters in Pennsylvania, a crucial political battleground state
won by Obama in 2008, said they were pessimistic about the state's
direction and unhappy with Democratic Governor Ed Rendell's job
performance.

A majority of voters, 55 percent, said the state was on the
wrong track and only 37 percent believed it was headed in the
right direction. Rendell's job performance as governor won
approval from only 43 percent, with 52 percent disapproving.

The struggling economy was the biggest problem on the mind of
Pennsylvania voters by far, with 48 percent putting it at the top
of the list over the budget deficit, which was second at 16
percent.

The little-known Sestak beat the veteran Specter in the
Democratic primary in May for the right to take on Toomey, the
former head of the conservative anti-tax group Club for
Growth.

Obama had endorsed Specter but a majority of 59 percent of
registered voters said Obama's backing of Specter made no
difference in their decision on how to vote.

In the governor's race, Republican Tom Corbett led Democrat
Dan Onorato among likely voters by a commanding 15 points, 49
percent to 34 percent.

The Ipsos poll of 600 registered voters, including 407 who
said they were likely to vote, was taken Friday through Sunday.
Interviews were conducted in English and Spanish.

The full survey of registered voters had a margin of error
of 4 percentage points. The smaller sample of likely voters had
a margin of error of 4.9 percentage points.
(Editing by Bill Trott)