An employee uses an iPhone at an Apple store in Beijing, Feb. 17, 2016. REUTERS/Damir Sagolj

SAN FRANCISCO — As the FBI and Apple head to court over an encrypted iPhone belonging to one of the San Bernardino, California, terrorist shooters, a parallel battle is shaping up in Washington, D.C., as legislators line up on either side of an issue that is pitting privacy advocates against national security hawks. Pressure is mounting on Congress on multiple fronts to deliver a bill that will establish uniform rules around how far tech companies must go in assisting law enforcement investigations, with several efforts now in the works.

With Republicans controlling both the House and Senate, it might seem that those calling for mandatory cooperation from the likes of Apple, Google, Microsoft and others would have the upper hand, but the issue is cutting across party lines.

Apple last week was handed a court order to create custom software that would allow federal investigators to unlock the iPhone of Syed Rizwan Farook, one of the two killers involved in the Dec. 2 San Bernardino shooting that left 14 dead. But Apple and most others within the tech industry argue that creating this software, a so-called backdoor, would set a dangerous precedent. If the technology were to fall into the wrong hands, it could ultimately give hackers, criminals and oppressive regimes unfettered access to the digital lives of tech users around the globe.

It’s a debate that’s continued in Washington since whistleblower Edward Snowden began his information leaks in 2013, but the recent clash between Apple and the FBI has brought renewed urgency to the discussion.

In Washington, lawmakers are forming alliances with rivals from across the aisle. Sens. Richard Burr, R-N.C., and Dianne Feinstein, D-Calif., reportedly have been working together on legislation. Their bill would penalize companies failing to decipher encrypted messages for authorities. At the same time, Sen. Ron Wyden, D-Ore., has previously introduced legislation that would prohibit federal agencies from making such requests.

The House is seeing similarly odd partnerships. For example, California Reps. Darrell Issa, a Republican, and Zoe Lofgren, a Democrat, both recently voiced their support for Apple and encrypted user privacy.

Lofgren argues that forcing U.S. companies to decrypt their software will simply move terrorists and criminals onto encrypted apps developed abroad. “If you take a view beyond this one bad case, which is indeed a bad case, you can see that in the end we're going to make Americans less secure but probably not do very much to fight real terrorists,” Lofgren told International Business Times.

If the feds keep pushing Silicon Valley to create backdoors into their technologies, the tech industry will retaliate by encrypting data more strongly, Lofgren said. “No doubt they will further encrypt their systems so that it’s impossible for them to break any aspect of it,” said Lofgren, pointing to the increase in encryption that took place following the Snowden revelations.

Indeed, it was amid those revelations that Apple created iOS 8, the first version of the company's iPhone software that is encrypted so strongly it's virtually impenetrable to hackers, even those working for Apple.

It’s not hard to understand why party lines have given way around encryption and backdoors, as the issues raised are stirring contradictory instincts even in the most committed partisans. Republican lawmakers, for example, are compelled to push for strong national security in most cases, but calling for backdoors would mean advocating for bigger government and more business regulation.

Democrats, meanwhile, have long been champions of Silicon Valley, a region that has voted blue in every presidential election since 1984. But it’s not easy supporting an industry whose products make it possible for criminals, hackers and terrorists to evade law enforcement. “It's very hard for any reasonable congressman to get behind a dead terrorist's cell phone privacy rights versus protecting the country,” Darren Oved, a partner at Oved & Oved, said.

It’s not just politicians with mixed feelings. Among voters, 55 percent of Democrats and 56 percent of Republicans said Apple should unlock Farook’s phone, according to a survey released Monday by the Pew Research Center.

For politicians, this divide means taking a stance that will potentially alienate about half the base. And that explains why many presidential candidates are avoiding the topic. Democrats Sen. Bernie Sanders of Vermont and former Secretary of State Hillary Clinton have both weighed in on the case between Apple and the Justice Department, but seemingly merely to acknowledge the complexities of the situation without taking a firm stance. Republican candidate Sen. Marco Rubio of Florida, who raised more money from Silicon Valley than anyone else in this election, followed suit.

"I really don't think that any of the candidates who are looking to raise money right now — say, Rubio, for instance — are going to take a strong position,” said Elliott Suthers, vice president at Highwire PR and the communications and media advisor for the McCain/Palin 2008 presidential campaign. “This issue is kryptonite.”

Republican presidential candidate Donald Trump, who has rarely shied away from alienating anyone, and rival Sen. Ted Cruz of Texas have called on Apple to comply. Only Trump, whose campaign is heavily self-funded, has gone so far as to call for an Apple boycott. “Boycott all Apple products until such time as Apple gives cell phone info to authorities regarding radical Islamic terrorist couple from Cal,” Trump tweeted Friday.

For the Justice Department and Apple, their differences will likely be settled in court. A date has already been set for a hearing March 22, and Apple, which is expected to appeal the court order by the end of the week, has already brought famed lawyer and former solicitor general Ted Olsen onto its defense team.

The case will raise a number of thorny issues surrounding privacy and the limits to government action. Obtaining a court order demanding Apple create custom software for the iPhone required the Justice Department to turn to the obscure All Writs Act, a law that is more than 200 years old. “In this case, no other statute addressed the procedures for requiring Apple to extract data from a passcode-locked iPhone,” the Justice Department wrote in a court filing Friday.

“There does need to be legislation that handles these issues. The technology has moved so far and so fast ahead of anything that the law used to account for,” said Justin Shiroff, an attorney with Snell & Wilmer and an expert on privacy and cybersecurity.

Further pressuring Congress to act are state legislatures, which have begun proposing their own laws. Some of these efforts would require phone manufacturers like Apple to be able to unlock their devices. One of these proposals was introduced by California Assembly Member Jim Cooper, a Democrat and former police captain. Cooper said he has dealt with child pornography and human trafficking investigations where access to a smartphone would have helped investigators.

"It’s those pics of human trafficking, girls being pimped, of children being assaulted and raped — those are going to be on those phones,” said Cooper, who believes the tech industry and law enforcement could compromise by keeping backdoor software in the hands of the tech companies. “Those phones hold critical evidence. That’s why people want the data"

Proposals like Cooper’s are forcing Congress to act. This month, Reps. Ted Lieu, D-Calif., and Blake Farenthold, R-Texas, introduced a bill that would prevent state legislatures from passing laws requiring tech companies to decrypt their products. Many experts agree it would be unrealistic to require Silicon Valley to comply with 50 different encryption standards.

“Congress must do its job,” said Morgan Reed, executive director of ACT | The App Association, a trade group that represents app developers. “It might not happen in 24 hours, but you are seeing that they know they have a job to do and that it's their responsibility.”