– The two contrasting Californians who lead House of Representatives oversight of U.S. intelligence operations will be tested as never before once Donald Trump becomes president.

The committee's chairman, Republican Rep. Devin Nunes, advises the Trump transition team. The top-ranking Democrat on the committee, Rep. Adam Schiff, assails the president-elect. Already, the two disagree over how Congress should handle allegations of Russian interference in the ­U.S. election.

Soon, Nunes and Schiff will confront other challenges, starting, perhaps, with Trump's apparent scorn for the CIA, the best-known of the 17 agencies that make up the intelligence apparatus.

"I have a lot of concerns," Schiff said in an interview. "I am concerned that the [new] administration is attacking the intelligence community [or] is ignoring it. Particularly for members of the minority, we're going to have a heightened responsibility."

At the same time, Schiff said, he and Nunes have established a "great working relationship." Though much of the work of the House Permanent Select Committee on Intelligence stays secret, evidence of good relations occurred when the two lawmakers joined forces Nov. 30 on the fiscal 2017 intelligence authorization bill, which easily passed the House.

The lawmakers have likewise retained a united front on other issues, as with their joint release Thursday of a report blasting former CIA employee and document-leaker Edward Snowden.

Their continued ability to avoid strictly partisan clashes could add credibility to their upcoming oversight work.

Some changes are certainly coming to the 22-member intelligence panel, where Republicans enjoy a 13-9 member advantage. At least five retiring or otherwise departing members will be replaced, probably including Rep. Mike Pompeo, a Kansas Republican nominated by Trump to head the CIA.

Membership changes can subtly alter committee dynamics. Pompeo, for one, was described by Schiff as being both highly capable and, at times, "very partisan." Another retiring member, Georgia Republican Rep. Lynn Westmoreland, is leaving behind the ­chairmanship of the subcommittee that oversees the National Security Agency and cybersecurity. That panel's role may grow with the Russian hacking probe.

In the new year, House committee members have been told to expect deep dives into the Russian hacking issue with on-site visits to multiple intelligence agencies. All the while, they'll keep up their regular closed-door meetings in the committee's secure underground hearing room and their often far-flung travels.

"We must make sure that intelligence is relevant in this new administration," Rep. Eric Swalwell of California said in an interview. "Right now, all the signals suggest President-elect Trump, without any basis, wishes to routinely undermine the patriots toiling away to keep us safe."

Highly coveted job

The House and Senate intelligence committees, membership on which is highly coveted, confront challenges under any administration. The defense and intelligence agencies are in the business of keeping secrets, even from those ostensibly on the same team. Inherent institutional motivations, from budget-seeking to self-preservation, inevitably lead to conflicts.

The Russian hacking investigation will test lawmakers' oversight talents on multiple fronts, from their ability to solve a mystery to their capacity for bipartisanship.

Nunes declared Dec. 12 that he does not see "any benefit in opening further investigations, which would duplicate current committee oversight efforts and intelligence community inquiries." Trump himself has questioned the CIA's reported conclusion that the Russians conducted the cyberattacks that breached Democratic National Committee ­computers.

"Unless you catch hackers in the act, it is very hard to determine who was doing the hacking," Trump asserted via Twitter on Dec. 12, several days after his transition office had bluntly dismissed the CIA as the "same people that said Saddam Hussein had weapons of mass destruction."

Nunes' insistence that the existing intelligence committees can manage the Russian hacking investigation is countered by some leading lawmakers, including Schiff and Swalwell, as well as hawkish Republican Sens. John McCain of Arizona and Lindsey Graham of South Carolina, who have called for forming a select panel dedicated to the hacking investigation.