U.S. Senator John Cornyn

Republican senators are worrying is President Trump has the legal authority to pay more than 1 million military service members during the government shutdown, The Hill reports.

The senators are "they’re frustrated that Trump once again appears to be trampling on Congress’s power of the purse," The Hill says.

Their concern stems from Trump's drifting from proper protocol in which the White House sends a request to reprogram federal funding to Capitol Hill and then members of the Appropriations Committee need to approve it before an administration is able to shift funds away from the programs for which they were intended.

Republicans say this did not happen before Trump ordered Secretary of Defense Pete Hegseth to use “all available funds” to make sure that members of the military got paid this week.

“That’s a concern of not just appropriators, it seems broader than that,” one Republican senator who requested anonymity told The Hill.

That senator also confirmed that their "Republican colleagues have asked the administration for more details about what accounts will be most impacted by shifting funds to pay the troops during the duration of the shutdown and what legal authority the White House is citing to justify its action," and received no answer.

Senator Susan Collins (R-ME), chair of the Senate Appropriations Committee, is also seeking more information from the White House.

“We’ve been given two different explanations. One, is that it’s unobligated balances. One, is that it’s taken from certain research and technology programs. But we don’t have the specifics. We have asked for the specifics,” Collins said.

Senator Lisa Murkowski (R-AK) also said she has "has concerns about Trump’s repurposing previously appropriated federal funding without input or approval from Congress," The Hill reports.

“I get that they say for the military pay for this pay period it comes out of … research and development technology [fund] but where? Is that taking it from projects that we have already identified? Maybe something’s really important to me. Where’s it coming from? We haven’t seen that,” she said.

Senate Appropriations Committee Vice Chair Patty MurrayPatty Murray (D-WA) told The Hill that she’s "not sure whether Trump’s repurposing of funds to pay troops is legal."

Rep. Jim Himes (D-CT) told The Hill that Trump’s reallocation of federal funding was “probably not legal.”

And while Republican Sen. Mike Rounds (R-SD) said that Trump does have the authority to do so, the anonymous senator disagrees.

“I’ve heard that, but I don’t know where that comes from,” the senator said