WASHINGTON — At an impasse on immigration, House Republicans and Senate Democrats advanced competing proposals Wednesday for dealing with tens of thousands of young migrants showing up at the southern border. Each side quickly ruled the other’s approach unacceptable, leaving any solution unclear with Congress’ annual August recess looming.

Unless Democrats capitulate, “We’re going to be at an impasse and we will have earned even greater disdain from the American people than we already have,” Sen. John McCain, R-Ariz., said.

But Republicans were having difficulty agreeing even among themselves.

At a morning meeting of House Republicans, Speaker John Boehner urged action to address the border crisis, reminding Republican lawmakers that the Border Patrol and other agencies would be running out of money in coming months because of the heavy influx of unaccompanied minors and families at the border.

A working group appointed by Boehner rolled out proposals including sending in the National Guard and changing a 2008 trafficking victims law to allow Central American kids to be turned around quickly at the border and sent back home. Lawmakers announced plans to chop President Obama’s $3.7 billion emergency spending request for the border crisis down to $1.5 billion.

But as they left the meeting in the basement of the Capitol, some of the more conservative members of the Republican caucus made clear they were unconvinced.

“If Republicans move forward on this, we’re now jumping right in the middle of President Obama’s nightmare and making it ours,” said Rep. John Fleming, R-La. Fleming said he worried that any House-passed bill “will be turned on its head” by the Senate “and actually make the problem even worse.”

Fleming said Boehner told Republicans he was undecided about bringing the plan to the floor because he didn’t know whether there were enough votes to pass it.