Washington (CNN) -- Opponents of a bipartisan Senate effort to reform the nation's immigration policies calculate that dragging out debate by offering so-called "poison pill" amendments designed to tank support and stoking conservative ire on the airwaves will derail the proposal.
It is a strategy that stymied the immigration overhaul efforts of 2007.
Legislative aides and the bill's supporters worry that with days running out in the congressional calendar and a heavy plate of issues before lawmakers, efforts to overhaul the nation's immigration system could get sidelined.
The so-called "Gang of Eight" senators who have labored for months, largely in secret, are expected to discuss their proposal at a press conference on Thursday.
But the pushback has already begun.
"It seems pretty clear that they are pursuing a strategy of trying to draw this out as long as possible because this bill has to get done as quickly as possible," said Deepak Bhargava, executive director of the Center for Community Change, which advocates for low-income communities.
"It's a ploy to try and throw sand in the gears and I suspect there will be a long list of poison pill amendments that will be offered through committee," Bhargava said.
Rep. Louie Gohmert, R-Texas, said on C-SPAN that Monday's Boston Marathon bombing illustrated potential security risks posed by immigration even though authorities have made no connection between the two.
Republican Rep. Steve King of Iowa told the National Review the attack should be an impetus to further investigate America's system of awarding student visas even though investigators have not linked it to any student or otherwise identified any suspects.
Other Republicans on the Senate Judiciary Committee, which is set to hold hearings on the measure on Friday and Monday, questioned what they see as the hasty pace of considering the measure and have asked for more public hearings.
"The bill produced by the "Gang of Eight" is nearly 1,000 pages long and will impact every aspect of our society and every single American worker and taxpayer. It will take months—not days or weeks as the majority proposes—to review this legislation," Alabama Republican Sen. Jeff Sessions said in a statement.
Last month, Senate Judiciary Committee Chairman Patrick Leahy, D-Vermont, sent a letter to several Senate conservatives urging them not to obstruct the upcoming legislative process relating to the issue.
"I hope it is not your intention to discredit the process," Leahy said. "I intend to proceed to comprehensive immigration reform with all deliberate speed. ... I hope and expect that you will not delay consideration simply to prevent the legislation from moving forward."
"Artificial delays, delays for delays' sake, has tainted too much of the Senate's work over the last few years," he added.
Leahy's letter was sent to Sessions, a high-ranking member of the committee. Panel Republicans Chuck Grassley of Iowa, Orrin Hatch and Mike Lee, both of Utah, and John Cornyn and Ted Cruz, both of Texas, also received copies of the letter.
The bill's supporters have ample reason to worry about their efforts crumbling.
In 2007, despite support from then-President George W. Bush and Republican Arizona Sen. John McCain, a bipartisan immigration proposal faced an avalanche of amendments on everything from increasing border security to creating a path to citizenship.
At the same time, Republicans who supported the proposal were castigated in their home states on conservative talk radio.
Republican Georgia Sen. Saxby Chambliss, who helped draft the bill, was booed at a state GOP conference when he tried to discuss the measure. Fellow Georgia Republican Sen. Johnny Isakson, who also helped draft the measure, received bricks at his office for a theoretical wall that could be used to build a border between the United States and Mexico.
Both lawmakers dialed back their support.
Ultimately, the slew of amendments and intense criticism from conservative circles buried the proposal. It was never voted on in the Senate.
"Last time their delay tactics were about trying to gin up through conservative talk radio grassroots opposition to the bill," Bhargava said.
This time, Florida Republican Sen. Marco Rubio, a potential 2016 presidential hopeful who has staked tremendous political capital on the bipartisan immigration reform push, is conducting interviews on conservative talk radio in advance of the bill's official roll out.
The political landscape is also different now and that might also help back efforts of the bill's supporters, said Stephen Yale-Loehr, an immigration attorney who teaches at Cornell University Law School.
"I think it is different from 2007 because there is a feeling that we do need to reform our immigration laws," Yale-Loehr said.
The Republican National Committee recently released a report analyzing its losses in the 2012 presidential election as well as seats in the House. It found that GOP presidential nominee Mitt Romney lost big among Latinos, African-Americans and Asians.
Romney's hardline stance on immigration, including his endorsement of a policy of "self-deportation," may be one reason why he won just 27% of Latino voters -- a lower percentage than the last two GOP presidential candidates. Since that loss, some Republicans have urged a softer tone and broader outreach in speaking to Latino communities.
"If Hispanic Americans perceive that a GOP nominee or candidate does not want them in the United States, they will not pay attention to our next sentence," the RNC report states. In one of its few policy recommendations, the report counsels Republicans to "embrace and champion" comprehensive immigration reform.
Still, it will be "hard to get all the moving pieces to align," Yale-Loehr said of getting lawmakers to agree on an overhaul. "The chances of getting something enacted this year are less than 50% because of the short number of legislative days and the House Republicans may not feel the same sense of urgency to enact immigration reform legislation."
CNN's Alan Silverleib contributed to this report.