If the Republican majorities in the House and Senate are unable to get legislation to President Donald Trump’s desk to keep the government running beyond an April 28 deadline, it could be a fairly historic political moment.

Not since President Jimmy Carter’s administration have a Congress and an executive branch unified under one party seen government funding gaps occur, according to the Congressional Research Service.

That was despite one funding gap during Carter’s administration that lasted 17 days — one of the longest appropriations lapses in the history of the modern budget process.

But hashing out a deal on fiscal 2017 — the most immediate political negotiation that could lead to a shutdown if unsuccessful — isn’t so simple for the GOP majorities who control today’s Congress either.

A highly conservative faction in the House that wants to see its priorities enacted in spending bills grates against a Democratic Senate minority that has the ability to block advancement of most legislation. The Senate needs 60 votes to advance spending bills and Republicans only hold 52 seats in the chamber.