Leading Capitol Hill opponents of a Senate proposal to overhaul the nation’s immigration system are coalescing around a strategy to kill the bill by delaying the legislative process as long as possible, providing time to offer “poison pill” amendments aimed at breaking apart the fragile bipartisan group that developed the plan, according to lawmakers and legislative aides.

The tactics, used successfully by opponents of an immigration bill during a 2007 debate in the Senate, are part of an effort to exploit public fissures over core components of the comprehensive legislation introduced Tuesday by eight lawmakers who spent months negotiating the details.

The authors of the bill, which was expected to be filed Tuesday night, are planning to formally embrace it in a joint news conference as early as Wednesday, a move designed to build momentum for the plan. But conservative critics cautioned Tuesday that the legislative process must not be rushed.

An open process “is essential to gaining public confidence in the content of the bill. We know it’s complicated,” said Sen. John Cornyn (R-Tex.), the top GOP member on the Senate Judiciary Committee’s immigration subcommittee. “I can’t see any reason to undermine confidence by trying to jam it through without adequate time for people to read it and to hear from their constituents.”

Sen. Charles E. Grassley (R-Iowa) called the pace of the legislative process — with Judiciary Committee hearings set for Friday and Monday — a “serious problem.” Rep. Steve King (R-Iowa) suggested to the conservative National Review that caution on immigration is important in light of early speculation that the Boston Marathon bombings might have been carried out by a foreign national with a student visa.

“I think it would force the people who have their hands over their own eyes and fingers in their ears to take a look from a different perspective,” King said in an interview with The Washington Post.

Authorities said Tuesday that there are no suspects in the bombings and that they have not determined whether the attack was domestic or foreign in origin.

Lessons from ’07

Democrats and immigration advocates, along with some GOP supporters, say they have learned from the failed immigration push in 2007, when a flurry of amendments on border control and a path to citizenship for illegal immigrants helped sink the legislation before it came to the floor for a vote.

Though the 2007 bipartisan legislation had support from President George W. Bush, the effort failed after an amendment to eliminate a new visa program for low-skilled foreign workers after five years was approved by a single vote, angering business groups and costing GOP support. Then-Sen. Barack Obama, at the time a presidential candidate vying for labor unions’ support, voted in favor of that amendment.

Sens. Charles E. Schumer (D-N.Y.) and John McCain (R-Ariz.), two members of the current working group, briefed President Obama at the White House on Tuesday afternoon.

“One thing he made clear is he wants to have an open process but he doesn’t want to delay and drag this out, because that’s the way bills get killed,” Schumer said. “That’s one of the most important points he made.”

Schumer said the goal is to have the Judiciary Committee open the bill for amendments in early May and get it to the Senate floor by early June. In a statement, Obama urged the Senate “to quickly move this bill forward” and pledged to “do whatever it takes to make sure that comprehensive immigration reform becomes a reality as soon as possible.”

Opponents take aim

The Senate working group comprises four Democrats and four Republicans, and members have agreed to band together to oppose any amendments of the core provisions.

But conservatives already are taking aim at several provisions, arguing that allowing undocumented workers to remain in the country amounts to “amnesty”; that the border control steps are not strong enough; that the guest-worker program will undercut Americans at a time of high unemployment; and that the bill will amount to trillions of dollars in new federal costs.

Those factors make immigration reform “a heavy lift,” said Kansas Secretary of State Kris Kobach, a lawyer who helped Arizona draft one of the nation’s strictest immigration laws in 2008. “Twenty million Americans are unemployed or under­employed. At any other normal time, no one would breathe about amnesty.”

But supporters say the political landscape has changed dramatically since 2007. Latinos overwhelmingly supported Obama’s reelection, and GOP leaders have said the party must do more to appeal to them.

Sen. Marco Rubio (R-Fla.), a member of the bipartisan group, has received tacit support from conservative talk-show hosts Rush Limbaugh and Sean Hannity after promising the tough border control measures will be in place before undocumented immigrants earn green cards.

“The theory in 2007 was the longer they could draw it out, a populist upsurge would bring down the bill,” said Deepak Bhargava, executive director of the liberal Center for Community Change, “but this time we’ll match them toe-to-toe.”

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