Working across party lines requires mutual trust. But that critical asset apparently is in short supply in the halls of national power.

Consider this extraordinary observation to reporters last Thursday from House Speaker John Boehner, R-Ohio:

"There's widespread doubt about whether this administration can be trusted to enforce our laws, and it's going to be difficult to move any immigration legislation until that changes."

That echoed this warning, four days earlier, from House Budget Committee Chairman Paul Ryan, R-Wis.: "Here's the issue that all Republicans agree on: We don't trust the president to enforce the law."

Critics charge that Reps. Ryan and Boehner are merely caving in to pressure from the hard right against what it sees as "amnesty" proposals on immigration.

Yet wary Republican lawmakers have a fair point about President Obama's credibility gap. The president has repeatedly issued executive orders to bypass the letter of laws - and has recently warned that he plans to more frequently invoke that authority.

In particular, the administration has frequently delayed, via executive fiat rather than legislative action, legally mandated implementations of the Patient Protection and Affordable Care Act.

But that doesn't justify summarily dismissing all hope of reasonable immigration legislation.

Instead, congressional Republicans should take President Obama up on his offer for incremental changes to immigration policy while insisting on firm legislative language that gives him little or no room for executive-branch end runs around the law.

The GOP should not, though, go for this unorthodox option presented by Sen. Charles Schumer, D-N.Y., Sunday on NBC's "Meet the Press":

"There's a simple solution - let's enact the law this year but simply not let it actually start until 2017, after President Obama's term is over."

Speaker Boehner's office quickly - and correctly - rejected that proposition as "impractical."

Yet insisting that no immigration legislation can be passed because the president isn't to be trusted is also impractical.

By all means, President Obama rates strong criticism - and not just by Republicans - for playing fast and loose with the checks-and-balances system of our national government.

However, GOP hard-liners against immigration reform should recognize the current opportunity presented by the desire of Democrats, including the president, to advance immigration reform.

They also should see that extending the status quo of a broken immigration system is irresponsible.

Worthy compromises still appear possible on this vital issue.

As Rep. Tom Cole, R-Okla., said Sunday on ABC's "This Week":

"I think step-by-step progress is still out there. Whether or not Democrats want to work that way I think is unclear. But you could clearly get a border security bill through. I think you can get H1B visas [for foreign workers with specialty skills] through. I think you could get seasonal labor. So I think there's still a path there."

And the best path on immigration remains overdue, balanced reform.