Other recommendations include repealing the Davis-Bacon Act, which requires paying prevailing wages, often union scale, on federal construction projects.

If Republicans decide to turn controversial platform items, like the transit proposal, into detailed legislative language, Democrats have enough Senate votes in the current Congress to block them.

Even if Republican nominee Donald Trump were to win the White House in November, getting the GOP platform items through the next Congress still would require a wider Senate Republican majority, which forecasters say isn’t likely.

The nonpartisan Rothenberg & Gonzales Political Report says the “most likely” Senate outcome is a Democratic pickup in November of three to seven seats. Democrats need a net gain of four Senate seats to regain the majority, the report notes.

Perhaps the most dramatic transportation construction proposal is the recommendation to end federal aid for transit. Bauer calls it  “a distinct departure from what they have done in the past four Republican platforms.”

The American Public Transportation Association strongly opposes the transit funding phase-out, APTA Acting President and CEO Richard A. White said in a July 19 statement.  He said, "Having no federal funds would be devastating" to riders, employers and local communities.

APTA notes that federal funds accounted for more than 40% of total transit capital spending in 2013 and expenditures still fall short of the level needed to improve the infrastructure and systems' performance.

The platform also says that federal funding for some other non-highway programs should wind down, including recreational trails, sidewalks, ferry boats, access to federal lands and historic preservation. The document does add that the non-highway projects are "worthwhile enterprises" that "should be funded from other sources." It doesn't specify those sources.

Transit has significant support in Congress. Indeed, last year’s Fixing America’s Surface Transportation Act—which passed the House and Senate by large bipartisan margins—included a larger funding increase for transit than for highways.

Bauer notes that many lawmakers know that the Highway Trust Fund, into which gas-tax receipts flow, has “a permanent deficit” that has necessitated a series of transfers from the general fund since 2008.

He says that eliminating trust-fund financing for transit would provide about $8.7 billion a year for other highway purposes, but the trust fund’s projected gap is much larger, totaling at least $18 billion a year starting in 2020, when the FAST Act expires.

The GOP’s opposition to a gas-tax hike isn’t surprising—many Republicans and some key Democrats have said for months, if not years, that they don’t support an increase.

Among the platform’s other transportation proposals, it says that Amtrak is “an extremely expensive railroad for the American taxpayers, who must subsidize every ticket.” It calls for allowing private entities to operate passenger rail on the Boston-to-Washington, D.C., Northeast Corridor.

Republicans also favor cutting off federal aid “for boondoggles like California’s high-speed train to nowhere.”

Construction has been underway since June 2015 on the $60-billion-plus California project, which has been scaled back from earlier plans.