But what looked insurmountable for Republicans at first is now viewed as a winnable race, officials in each party said.

"They see it as a winnable race" for the Burrows seat.

"This has definitely progressed as a campaign to the point where we think this is a very winnable race."

"This is a winnable race," Ms. Kilroy told the union men.

"This is a very winnable race for him," said Fred Yang, a Democratic pollster.

From his perspective, Mr. Cuomo added, there is another, more important and ultimately winnable race.

But we still kept the payments up because it seemed like a winnable race.

But it's a winnable race.

Mr. Crowley "is a formidable candidate," he said, "but the race is a winnable race."

What had seemed a winnable race for the Democrats became much tougher overnight, strategists said.