SALT LAKE CITY (AP) — An unlikely political friendship spawned a compromise proposal Tuesday for a massive shipping hub in Salt Lake City, but some remain skeptical.

The plan would tweak a contentious law that critics say was a power grab by conservative state leaders at the expense of Democratic city officials.

It calls for increased environmental protections at 20,000-acre (8093.89-hectare) facility, covers on coal shipments, more city control over land-planning and assurances that municipal leaders will keep control of airport operations, among other things.

Outspoken Democratic state Sen. Jim Dabakis and powerful Republican House Speaker Greg Hughes said they spontaneously agreed to the compromise after an argument on a local Sunday-morning political talk show. Both are departing the state Legislature: Dabakis is considered a possible candidate for mayor in Salt Lake City and Hughes may run for governor.

"We disagree, we are fundamentally opposed in everything, but in America ... this is how we kind of move forward," said Dabakis, who represents Salt Lake City. Both men declined to discuss their political futures.

City leaders sounded a note of cautious optimism on the compromise.

"Dialogue is always very important," said David Litvack, the mayoral deputy chief of staff. "The devil is always in the details."

Other Democratic state lawmakers, though, blasted the plan as a back room deal. Skeptical residents also spoke up several times during Tuesday's news conference to say it wouldn't do enough to mitigate truck traffic, coal shipments and pollution in a city with persistent dirty-air problems.

State lawmakers this year passed a law outlining plans for the shipping hub that would take goods from West Coast seaports and elsewhere, then store and process the cargo before it's transferred onto trucks and railcars.