Freshly empowered California Republicans in Congress are pushing the Trump administration to hold off on approving $647 million for the Caltrain system to go electric — something that could kill the redo of a line that carries more than 60,000 riders a day between the South Bay and San Francisco.

“It’s critical that we get the funding,” said Caltrain spokesman Seamus Murphy.

In a Jan. 24 letter to newly sworn-in Transportation Secretary Elaine Chao, all 18 members of the state’s GOP congressional delegation called for the Caltrain money to be put on hold until a full audit is done on Gov. Jerry Brown’s high-speed rail project.

The Republicans don’t have anything against Caltrain electrification per se — it’s the high-speed rail line they can’t stand. And high-speed trains will have no way of getting from San Jose to San Francisco if the Caltrain line isn’t electrified.

Caltrain says that if its federal funding is delayed — even for a couple of months — it could mean having to rebid the work already being contracted out. Losing the money entirely would effectively kill electrification of the line.

Republicans have long seen high-speed rail as a boondoggle, but they’ve been up against an Obama administration that refused to spike its funding. That’s not a problem anymore.

Caltrain and its advocates hope the tech titans along the Peninsula and in the South Bay can convince the Trump administration of the project’s pluses. One such plus: the jobs that electrification will create both here and in red states like Utah, where 500 people are to be put to work building new train cars for the line.

A decision is due soon — the funding renewal will be on Chao’s desk for signing by mid-February.

San Francisco Chronicle columnists Phillip Matier and Andrew Ross appear Sundays, Mondays and Wednesdays. Matier can be seen on the KPIX TV morning and evening news. He can also be heard on KCBS radio Monday through Friday at 7:50 a.m. and 5:50 p.m. Got a tip? Call (415) 777-8815, or email matierandross@sfchronicle.com. Twitter: @matierandross