By Thomas Ferraro and Richard Cowan

WASHINGTON (Reuters) - A third Republican U.S. Senate candidate on Wednesday rejected Mitt Romney's characterization of nearly half the country as slackers, but other party lawmakers voiced support for their struggling presidential nominee.

Republican members of Congress said Romney was making a valid point, though not artfully stated, when he said that 47 percent of Americans pay no federal income tax and feel entitled to federal assistance.

They predicted that the remark, which has triggered a political firestorm, would quickly fade without hurting Romney or their own chances for re-election.

But President Barack Obama's Democrats are pushing to make it an issue in the presidential and congressional campaigns, even quickly coming up with new ads.

Senate Democratic Leader Harry Reid ridiculed Republicans, telling reporters: "We have a long line of people who are running from Romney."

Reid cited three Republicans in close Senate races who have rebuked Romney's comments - Senators Scott Brown of Massachusetts, Dean Heller of Nevada and Linda McMahon, who is running for the Senate in Connecticut.

Brown and McMahon rejected Romney's comments on Tuesday, shortly after the release of a video showing Romney speaking at a private fundraiser earlier this year.

At the event, Romney essentially wrote off as Obama backers 47 percent of Americans who "pay no income tax" and see themselves as "victims" who are "entitled to healthcare, to food, to housing, to you name it."

In a brief interview on Wednesday, Heller, whose father was an auto mechanic and mother was a school cook, said, "I disagree with his statement."

Heller said plenty of blue-collar families, like his own, worked hard to pay their bills and make it on their own.

"We should be talking about creating jobs - not about 47 percent who aren't paying taxes and may be on some sort of assistance," Heller said.

Romney's comments have drawn fire from a number of leading conservatives who describe his campaign as sputtering, allowing Obama to build a lead in the polls.

Republican Senator John McCain, his party's failed 2008 presidential nominee, fired back at Romney's critics, saying, "We don't need people second guessing the nominee of our party."

"I had a lot of that in 2008. I didn't appreciate it at the time. I don't appreciate it now," said McCain, who offered his interpretation of Romney's remarks.

"He was saying, and I agree with him, that we need a good economy (to) create jobs so people can get off subsistence programs," McCain said.

While a number Republicans stood up for Romney, publicly dismissing the controversy and voicing support for their nominee, others privately voiced concern.

Senate Republican leaders apparently didn't want to talk about it. They ended their weekly news conference about issues before Congress without taking any questions.

A senior congressional Republican aide, speaking on the condition of anonymity, called Romney's remarks "completely bone headed."

"There are two things you can't be in politics: corrupt or out of touch. This builds on the narrative that he's out of touch with struggling Americans," the aide said.

A poll released on Wednesday by Pew Research Center found Obama leading Romney, 66 percent to 23 percent, as the candidate who best connects with ordinary Americans.

A Republican leadership aide predicted Republicans will stand firmly with Romney despite a couple of tough weeks.

"People aren't happy with the way the campaign has been going, but we still have time to win and still feel the economy will be the top issue," the leadership aide said.

Republican Senator Charles Grassley said the Republican nominee needs to step up.

"It's an opportunity for him to do what he hasn't done enough of: emphasize the economic differences and economic philosophies between the two parties and between the two presidential candidates," said Grassley, who is not up for re-election until 2016.

Republican Senator Kelly Ayotte said: "I know that he (Romney) cares about every American ... His vision is one that he wants every American to have opportunities and a good paying job."

Republican Senator Patrick Toomey dismissed the furor over Romney's "47 percent" comment.

"The sense is that press is over-playing it and that Romney is in a strong position," Toomey said, citing the weak economy and Obama's failure to remedy it.

While others have urged Romney to shake up his staff and detail his plans to boost the economy, Toomey said, "He doesn't need me to tell him what to do. He has a plan. I'm sure he will focus on the economy as he has been doing."

(Editing by Lisa Shumaker)