"They got a lot of things done with bipartisan support, but right now it's just difficult to imagine,” Bush, brother of the 43rd U.S. president and son of the 41st, said in a round-table discussion with reporters and editors held by Bloomberg View in Manhattan.
"Ronald Reagan would have, based on his record of finding accommodation, finding some degree of common ground, as would my dad — they would have a hard time if you define the Republican party — and I don't — as having an orthodoxy that doesn't allow for disagreement, doesn't allow for finding some common ground."
Bush, a moderate believed to be eyeing a run for president in 2016, called the partisanship disturbing, but added he thinks it's "temporary."
And even though some high-profile Republicans said their No. 1 goal was to deny Barack Obama a second term shortly after his election in 2008, Bush blamed the president for the hyper-partisan state of affairs that's been infecting the U.S. capital ever since.
"His first year could have been a year of enormous accomplishment had he focused on things where there was more common ground," Bush said.
Bipartisanship was commonplace during the Reagan and George H.W. Bush administrations, Bush added.
"Back to my dad's time and Ronald Reagan's time — they got a lot of stuff done with a lot of bipartisan support," he said.
In today's political climate, he added, Reagan "would be criticized for doing the things that he did."
Obama's re-election team pounced on Bush's remarks, emailing them to reporters almost as soon as they showed up on the Buzzfeed website as evidence that even leading Republican voices are put off by the hardline tactics of today's band of congressional Republicans.
For Obama, it was a rare opportunity to watch Republicans struggle with the same type of bitter pill he's been choking back in recent weeks — a Mitt Romney surrogate straying off message just six months before the presidential election.
Both Bill Clinton and Mayor Cory Booker of Newark, N.J., have recently caused headaches for Obama's re-election team by defending Romney's business record.
It's the second time in the past two weeks that Bush, the former governor of Florida, has broken with his party.
Earlier this month, he told a congressional hearing that he would embrace a debt reduction plan that exchanged $10 in spending cuts for a dollar in tax increases. Republicans have been dead set against raising taxes to tackle the country's mammoth US$15.7 trillion debt.
Bush also pointed out he refused to sign a "no new taxes" pledge by conservative anti-tax crusader Grover Norquist. Many Republican lawmakers have signed the pledge; Romney did so in 2008.
Norquist responded snidely to Bush's latest remarks.
"That's foolish," he told the Talking Points Memo website, saying Bush's father "threw away" his presidency on a promise of a 2:1 ratio of spending cuts to tax increases.
"And he thinks he's sophisticated by saying that he'd take a 10:1 promise? He doesn't understand — he's just agreed to walk down the same alley his dad did with the same gang. And he thinks he's smart. You walk down that alley, you don't come out."
In another comment that some might regard as a gift to Obama, Bush said he doubted any president, Republican or Democrat, is going to have much success reigniting the struggling U.S. economy anytime soon given the fiscal crisis facing Europe and a slowdown in Asia.
"We're in a period here for the next year of pretty slow growth; I don't see how we get out, notwithstanding who's president," he said.
He also had some advice for Romney on an issue that bitterly divides Republicans: immigration. The former Florida governor said Romney needs to reach out to Hispanic voters who overwhelmingly vote Democrat in presidential elections.
"He needs to broaden the message out when talking about immigration, to make it an economic issue as much as it is a question of the rule of law," said Bush, a long-time immigration advocate who's been married to a Mexican woman for almost 40 years.
"Have a broader message and have a more intense message."
Debates during the Republican primary season focused on keeping illegal immigrants out of the country rather than examining how to accommodate the millions already in the U.S., Bush noted. That hasn't won the party many fans among Hispanics, the fastest growing demographic in the country.
"There is work to do," he said.
Romney's successful attempts to reach out to primary voters who are anti-immigration has left him in a difficult spot, he added.
"Gov. Romney has used this as a means to connect with a group of voters that were quite angry, and it was effective," he said. "But now he's in ... somewhat of a box."
Bush added, however: "I do feel a little out of step with my party on this."
He also put in yet another plug for Florida Sen. Marco Rubio, the son of Cuban immigrants, as Romney's running mate.
"He is more mature than his age, more experienced than you would believe, more articulate than, I believe, President Obama — without a TelePrompTer," Bush said. "He would bring energy to a campaign that could always use it. He's the real deal."