For the Republicans in Washington who hoped a new bipartisan push for immigration reform would give their party a fresh start, a new face, and a second chance with Latino voters, 2013 is instead reviving some of their worst memories.

The legislation currently winding through the Senate with the help of party superstar Sen. Marco Rubio is still very much in play, and could well become the first law in a generation to address the country's immigration morass. But as conservative criticism of the reform effort grows louder, many Republican operatives, donors, and consultants are bracing for an outcome that would be even worse, politically, than the demise of the bill: a fierce, national, right-wing backlash that drowns out the GOP's friendlier voices, dominates Telemundo and Univision, and dashes any hopes the party had of making inroads to the Hispanic electorate by 2016.

"We are really balanced here on a little precipice, and if this, pardon the pun, goes south, we could be in very serious trouble," said Republican media strategist Paul Wilson, citing the increasingly intense attacks on the immigration bill coming from the right. "If [the legislation] stalls or is killed off by conservatives, we could take the Hispanic community and turn them into the African-American community, where we get 4% on a good day... We could be a lost party for generations."

Establishment Republicans don't have to reach too far back in recent history to find precedent for this political nightmare scenario: It would look a lot like the last time Congress pursued comprehensive immigration legislation.

In 2007, the conservative war on immigration reform — an issue that had, until not long before, been relegated to the second tier of American politics — was being waged on two fronts.

In Washington, George W. Bush's administration was working feverishly alongside Senate Majority Leader Harry Reid to get what was then known as comprehensive immigration reform through the Senate. While objections to the plan to offer undocumented immigrants a path to citizenship came from both sides of the aisle, it was the conservative gadflies like Colorado Rep. Tom Tancredo — who called for an indefinite moratorium on all immigration to the U.S. and championing a Constitutional amendment to make English the national language — who got most of the attention.

And as the battle on Capitol Hill wore on, the mood among reform advocates grew grim. Grover Norquist, a conservative leader and longtime immigration advocate, recalled attending strategy meetings with Barry Jackson, then a senior Bush advisor, where attendees tried to keep spirits up by means of delusion.

"It was like Hitler's bunker, where you know you're losing but you're still like, 'Here's our counterattack!'" Norquist told BuzzFeed. "We tried to pretend like we could still win, but we knew it wasn't going to happen."

The impending defeat was all the more frustrating for Norquist and his Republican allies because they could see how the battle was hurting their party's image among Latinos. Norquist blamed Democrats for deliberately sinking the immigration effort in 2007 and said the GOP got unfairly saddled with the blame — but he allowed that conservatives in his party didn't help their case.

"Tancredo was out there screaming every day, and if you were watching Univision, it would say the Republicans appear to be killing the bill," he said. "That remains the danger this time."

Meanwhile, in city council meetings, town halls, and border towns across the country, the grassroots fight over immigration was reaching a fever pitch.

A group of self-appointed border guardians who called themselves the Minutemen had evolved from a strange object of curiosity in the mainstream media to a symbol of the right's perceived anti-immigrant fervor. B-roll of shotgun-wielding militia men camped out in the southern desert was played on a constant loop on Spanish-language networks. In August 2007, a group of San Diego Minutemen drew national attention when they posted to YouTube a video shot from the perspective of a night-vision gun scope that depicted an illegal border-crosser being murdered. The men who made the video eventually said it was staged and that it was intended as a protest against Bush's "Amnesty Bill."

Elsewhere, local politicians tried to take advantage of the new wedge issue by passing hard-line ordinances. In Farmer's Branch, Texas, for example, the city council passed a measure that made it illegal for landlords to rent to undocumented immigrants. When residents petitioned to put the measure to a vote, it became the subject of a heated special election in the summer of 2007, with the two sides occasionally clashing physically as they canvassed the same working-class neighborhoods. In the final days of the campaign, the mayor, who opposed the measure, got a brick thrown through his window, and federal authorities reportedly advised him to leave town.

In Hazleton, Pennsylvania, Mayor Lou Barletta helped pass the controversial Illegal Immigration Relief Act, which penalized employers for hiring undocumented immigrants and cracked down on landlords renting to them. The city council also passed an act to make English the official language of Hazleton.

"Enough was enough," Barletta, now a congressman, said recently as he recalled the period. "I realized that illegal aliens were getting more rights than you as a United States citizen could have. And I began my crusade. If a small town like Hazleton could be affected, there were others around the country."

The conservative backlash provoked a new militancy among immigrants as well: Advocates for the undocumented began holding massive counterprotests in Los Angeles, Dallas, and other cities with large Latino populations.

But the conservative campaign to kill the immigration bill in Washington ultimately succeeded — at a high electoral cost. Whereas exit polls in 2004 showed Bush receiving upwards of 40% of the Latino vote, that figure plummeted to about 31% for John McCain in 2008, and 27% for Mitt Romney last year. The reasons for the Hispanic exodus are complex and varied, but few Republican strategists these days will argue with the notion that the 2007 culture war on immigration reform stained the party's brand.

Six years later, as a new bipartisan immigration bill makes its way through the Senate, anxious Republicans are worried that the cycle is beginning to repeat itself.

"Go to sites like RedState or Breitbart and search headlines about immigration and Rubio, and then look at the comments. Some of them are really, really nasty," said one prominent Republican strategist who spoke on condition of anonymity. "That's the thing that I worry about a little bit. That kind of tells me that the harsh xenophobic thing from 2007 could be coming back."

The strategist added that a large-scale conservative campaign against immigration reform would be particularly disastrous if the bill actually passes, creating millions of new Latino voters over the next decade who would be tasked with choosing between the party whose president signed the reform measure and the party whose members fought to keep them out.

And there are signs that the immigration hard-liners are waking up. Rubio has been fending off increasingly sharp attacks by the conservative media, and many Republicans in Congress are becoming more vocal in their skepticism of the bill.

"We've held our powder dry and have decided to come forward now because ... we are concerned about having this wash over us and not having the opportunity to have constitutional conservatives in this country and in this congress have their voice heard," Rep. Steve King told reporters earlier this month. "We don't have a moral obligation to legalize people who are here illegally."

But there is also evidence that the political climate has fundamentally changed since 2007. Conservative religious organizations are actively lobbying in favor of immigration reform this time around. Key conservative opinion-makers like Sean Hannity and Bill O'Reilly have transformed themselves into immigration advocates. And, perhaps most strikingly, those on the right who tried this month to tie the Boston Marathon bombings to immigration policy have been relatively muted.

"If this were 2007, you can imagine how the talk radio people might have reacted," said Norquist. "They might have gone, 'These people are bad, and they're squirrely looking, and they're immigrants!'"

Norquist, one of his party's most successful organizers of the last 20 years, said he recently hosted a meeting with conservative immigration hard-liners who believed "they could put the old band back together" and revive the culture war of 2007. Rather than lecture them on how their crusade would adversely impact the GOP, he presented polling data to show just how fruitless their efforts would be.

"Guys, the world has moved from beneath you," Norquist said he told them. "If you guys think you can just jump out and yell 'amnesty!' like a magician saying a magic word and everyone freezes, it's just not true anymore. Everyone just looks at you and says, 'What are you talking about?'"