"There is still room for someone to emerge as the conservative alternative to Romney," Reed said.
Most veteran Republicans don't believe that person will be Trump, the thrice-married, much-caricatured developer who has donated heavily to Democrats in past years and switched his stands on key issues such as abortion.
Karl Rove, the top political adviser to President George W. Bush, calls Trump a "joke candidate."
Jennifer Horn, a 2008 Republican congressional nominee from New Hampshire, said in an op-ed column that Trump has flip-flopped on major issues and is not a credible candidate. If Republicans allow him to "hijack the primary process then they deserve exactly what they get," she wrote.
Over the years, Trump has given thousands of dollars to Democratic candidates, including New York Sens. Chuck Schumer and Kirsten Gillibrand and Senate Majority Leader Harry Reid of Nevada.
Trump talked of running for president as a third-party candidate in 2000, and he made a brief splash with a 1988 New Hampshire speech that some took as a preliminary Republican candidacy.
In New Hampshire on Wednesday, Trump breezily dismissed his critics.
"I think I'm quite conservative as a Republican," he told reporters in Portsmouth. In at least two instances, he said, "I'm leading the polls." Forcing Obama "to finally come out and issue a birth certificate can only help," he said.
Trump said he has given campaign money to "many Republicans, many Democrats. And I think there's something nice about that," because it promotes bipartisanship.
As for switching his stand on issues, he said, "My views change. ... I tell people, you have to remain flexible because the world changes."
He also turned the conversation to Obama.
"Nobody even knows what's going on in Libya," Trump said. He said Obama claims to have little control over gasoline prices, but "he does if he gets on the phone or gets off his basketball court or whatever he is doing at the time."
After holding court before reporters, Trump traveled to several other stops, all within a nine-mile radius of the Portsmouth airport.
He spent a few minutes shaking hands at a Portsmouth diner but spent little time in conversation. Passing by a table of older men, he waved and said, "Why aren't you at work?"
"We're retired!" answered the group of former workers at the Portsmouth Naval Shipyard.
"Don't touch Medicare, right?" Trump said, moving on without waiting for an answer.
Joe Lovell, of Somersworth, said seeing Trump arrive by limo was a surprise in this state that values close contact with presidential hopefuls.
Asked what he thought of Trump, he said, "Nice hair."
- Live at the GOP convention: Donald Trump...
- Group: Half of Syrian refugee kids in Lebanon...
- Marilyn Monroe's tresses and dresses going up...
- IOC explores legal options on banning all...
- Utah pledges all votes to Cruz after Trump...
- Trump's party: What to watch on GOP...
- Friends recall slain officers as residents...
- No sign of Trump endorsement, but plenty of...
- Utah delegates finally stand and cheer... 93
- Utah GOP delegates finally fired up... 74
- Did the Republican Party just adopt the... 48
- Obama rejects Trump depiction of US in... 39
- The day after: Lee defends Cruz at GOP... 30
- Trump speechwriter apologizes for... 27
- Police give all-clear in Munich... 25
- Thunderous boos for Cruz for refusing... 22