WASHINGTON - The push-pull of immigration reform is intensifying as Congress prepares to return to work for one of the last few legislative sessions before the midterm elections.

The window for Congress to approve an immigration overhaul is closing, but House Speaker John A. Boehner continues to suggest that action is still possible.

Boehner (R., Ohio) is racing the clock this summer, against not only the November election, but also the threat that the White House will take administrative action if Congress fails to act.

President Obama has made it clear that his patience has worn thin as House Republicans dabble in the issue, almost a full year after the Senate, controlled by Democrats, approved a sweeping bipartisan immigration law overhaul. Obama has directed the Homeland Security Department to review the way immigration laws are handled, and emphasis of that report is expected to fall on curbing deportations.

But here's the rub: Every time the White House threatens executive actions, it drives Republicans further from any compromise with Democrats. Republicans aligned with the tea party argue that the president would merely pick and choose which parts of new legislation he would enforce.

In a letter this week warning Obama against the Homeland Security review, 22 Republican senators raised the trust argument. "Our entire constitutional system is threatened," they wrote, "when the executive branch suspends the law at its whim."

Most observers believe that the opportunity for immigration reform during this Congress has long passed and that this summer will provide a lot of talk but little action.

Then again, Boehner knows how important the issue is for the GOP as it tries to broaden its base of mostly white voters, especially heading into the 2016 presidential campaign.

The short legislative calendar could present a venue for testing GOP immigration-reform bills.