More than half of Congress has never debated immigration reform

More than half of Congress has turned over since the last time the House and Senate tried to move legislation to overhaul the nation's immigration laws.

The high turnover rate bolsters the argument of Republican leaders, who say Congress must move methodically on immigration. President Obama, meanwhile, has pushed for swift passage of a bill, saying lawmakers have long debated the issue.

Only 54 current senators were in the Senate in June of 2007, when the upper chamber last voted on comprehensive immigration and border-security legislation. And just five of the 23 GOP senators who voted in favor of the 2006 immigration reform bill are still serving: Sens. Lindsey GrahamLindsey GrahamRomney should endorse Clinton Graham: I'm still not supporting Trump North Korean official calls Trump idea of meeting 'nonsense' MORE (S.C.), John McCainJohn McCainMellman: Parsing the polls GOP seeks to remove funding to design Gitmo alternative Big-name donors join Trump fundraising team MORE (Ariz.), Susan CollinsSusan CollinsGOP lawmaker: 'Republicans were wrong’ to block Garland Senate passes broad spending bill with .1B in Zika funds Senators unveil bill to overhaul apprenticeship programs MORE (Maine), Lisa MurkowskiLisa MurkowskiOvernight Energy: Lawmakers closing in on chemical safety deal GOP chair pushes Obama official on Arctic drilling plan McConnell touts 'Senate squad' in Wes Anderson-style video MORE (Alaska) and Mitch McConnellMitch McConnellOvernight Healthcare: House loosens pesticide rules to fight Zika | A GOP bill that keeps some of ObamaCare | More proof of pending premium hikes Senate votes to block financial adviser rule Reid defends embattled VA secretary MORE (Ky.).

In the House, the turnover has been higher since the lower chamber last cast a major vote on immigration at the end of 2005.

Fifty-eight percent of new House members have taken office since then, meaning less than half of the lower chamber took part in the last significant legislative battle over tightening the border and granting legal status to the nation's illegal immigrants.

The high level of turnover suggests it’s hard to predict how negotiations will fare, as a number of lawmakers haven’t yet indicated where they stand. It could also slow down the pace of legislation.

There are potential upsides in the high turnover rate for reform advocates, however. New sets of eyes on the legislation, and new ways to discuss immigration policy, could translate into a different ending for a bill this Congress.

For example, freshman Sen. Marco RubioMarco RubioNew Mexico GOP gov. won’t attend home-state Trump rally Rubio: 'It’s not that we lost, it’s that Donald Trump won’ Santorum endorses Trump after 'long heart-to-heart' MORE’s (Fla.) is among the GOP leaders on immigration and has so far skillfully navigated the thorny matter.

“There's an opportunity and a challenge,” said America’s Voice Executive Director Frank Sharry, a top immigration reform advocate who was involved in the last round of negotiations. “The key is going to be whether a whole crop of new lawmakers say, 'Hey man, I get it, this is sound.' We haven't been able to break through the white noise before. Here's our chance.”

Another factor: Few Republicans backed the bill even though then-President George W. Bush lobbied hard for it in 2006 and 2007.

There is a much bigger political impetus for the GOP to resolve the issue following their 2012 losses, and Rubio is perhaps better liked by the GOP base now than Bush was after he led his party to a drubbing at the polls in 2006. But if a sitting president couldn’t rally members of his own party around his bill, it’s unclear whether pro-reform Republicans will be able to do any better this time.

The 2006 vote on the McCain-Kennedy bill is the best comparison to the current bill, because the June 2007 vote on a bill co-sponsored by the late Edward Kennedy (D-Mass.) and then-Sen. Jon Kyl (R-Ariz.) had many senators who’d once supported the legislation bail out when it was clear it would fail. The Kennedy-Kyl bill died on the floor after a fight over a series of amendments portrayed as "poison pills" that would sink the measure, including one sponsored by then-Sen. Illinois Barack ObamaBarack ObamaDems discuss dropping Wasserman Schultz Mellman: Parsing the polls LA mayor: 'Donald Trump will not win California' MORE.

Of the Democrats who opposed the bill in 2006, only Sen. Debbie StabenowDebbie StabenowDems: GOP playing from 'Trump textbook' Will Republicans put up more bureaucratic obstacles to healthy kids? Let’s stand with retired military leaders to get healthy school meals over the finish line MORE (Mich.) is still around. Yet, nine current Democratic senators, including three members facing challenging reelection races next year, voted against a key procedural motion on the 2007 Kennedy-Kyl bill. Many GOP Senate opponents remain: Of the 22 who remain from 2006, 17 voted against both reform bills.

House Judiciary Committee Chairman Bob GoodlatteBob GoodlatteHouse Republicans press case for impeaching IRS commissioner Saudis scramble for Washington allies IRS hearing: Five things to watch MORE (R-Va.) told The Hill earlier this month that his panel would move at a deliberate pace on immigration, in part because Republican leaders need to educate more than 100 first- and second-term members. He said these legislators “know very little” about the complexities of immigration law.

“We’re going to be aggressively pursuing the issue to see if we can do something that is — I won’t call it all-encompassing, but that encompasses a number of the different issues that are addressed in immigration,” he said.

Obama has warned that if Congress doesn’t move fast enough on legislation, he’ll seek a vote on his own bill. Over the weekend, a draft White House immigration bill was leaked to the press. Rubio’s office blasted the move, arguing that the White House was injecting “additional partisanship into an already difficult process.”

Obama has since called on Rubio and other Republicans to lower the temperature on immigration.

Proponents of comprehensive immigration reform have been pushing hard to educate House members on the issue, and remain optimistic that the political pressure on the GOP to get something done has changed the conversation.

“The risks are not everyone is as familiar with the pitfalls and the details,” said National Immigration Forum Executive Director Ali Noorani. “But the pros outweigh the cons. This is not the 2006 immigration debate. The electoral and constituency dynamics are completely different, and with that comes a different kind of space for policy development.”

Noorani has sought to mitigate those problems by organizing a coalition of faith leaders, law enforcement officers and business leaders to lobby undecided Republicans — especially newer members. He’s been meeting with lawmakers for more than a year and the group has ramped up its efforts since the November election.

“We knew that the power of the Latino, Asian and immigrant vote was going to get us 60 to 70 percent there [to passing a law], but the balance between that and getting to a win means Republicans need to hear from their base of why immigration reform is so necessary, especially with the new members,” he said. “What we did is try to anticipate the needs and concerns of members who didn't know the issues well. ... Behind the scenes and quietly, we're doing those conversations on the Hill so they can ask questions about policy and legislative strategy.”