Facing a divided House Republican conference and no clear path forward on legislation to address the border crisis, Speaker John Boehner is giving President Barack Obama an ultimatum: support reforms to toughen up border controls or we won’t give you any money to deal with the humanitarian crisis involving child migrants from Central America.

Specifically, Boehner wants Obama to push Democrats to change a bipartisan 2008 anti-trafficking law that prohibits U.S. officials from quickly sending away children at the border who aren’t from Mexico or Canada.

“Frankly, it is difficult to see how we can make progress on this issue without strong, public support from the White House for much-needed reforms, including changes to the 2008 law,” the Ohio Republican wrote in a letter to the president on Wednesday afternoon. He signaled the House “will not support providing additional money unless you work with both parties to address the causes of this tragedy.”

The challenge is that Democrats — including Senate Majority Leader Harry Reid (D-NV) and House Minority Leader Nancy Pelosi (D-CA) — oppose changes to the 2008 law, which was designed to protect children from trafficking and smugglers.

A White House spokesperson didn’t immediately return a request for comment on Boehner’s letter.

Boehner’s letter comes hours after a working group of House Republicans led by Texas Rep. Kay Granger unveiled a set of proposals to stiffen border security, which included amending the 2008 law to make it easier to send the undocumented children back home quickly. But Boehner was cagey about which, if any, proposals would come up for a House vote in the 6 remaining working days before Congress adjourns for a five-week summer recess.

Multiple sources say Congress is unlikely to pass any border supplemental before the August recess. The prospect of inaction is making lawmakers — particularly members in border states, such as Arizona Rep. Matt Salmon — nervous about catching an earful from constituents back home if they leave Washington without doing anything about the problem.

Senate Democrats announced a competing emergency funding proposal on Tuesday to speed up the processing of the more-than-57,000 child migrants that have crossed the border in recent months and overwhelmed the system. The proposal, unveiled by Senate Appropriations Chair Barbara Mikulski (D-MD), pared down Obama’s $3.7 billion request to $2.7 billion. It didn’t include any changes to immigration laws.

“This is a funding bill, so it does not include immigration legislation,” Mikulski said. The money would be used to buy additional facilities to house the children and bring in new judges to speedily determine whether they qualify for asylum or must be sent home.

Last month, the Obama administration expressed openness to changing the 2008 law, before Democratic leaders and some rank-and-file members voiced their opposition to efforts in Congress to do that. Rep. Luis Gutiérrez (D-IL) said Wednesday that “Democrats have children to protect and the Republicans have a crisis to exploit.”

House Republicans also want to spend less than the White House and Democrats: Boehner floated a funding level of $1.5 billion for the border crisis. The House GOP’s ideas are meeting a chilly reception among Senate Democrats.

“Nobody here likes it one bit,” said Vincent Morris, a spokesman for Mikulski.

It’s plausible Senate Democrats will advance their $2.7 billion supplemental next week, sources say. But the fate of even that bill is uncertain as they’d have to defeat a filibuster expected from Senate Republicans, whose leadership has also demanded changes to the 2008 law.

“A few weeks ago, the president made some modest policy recommendations that should be part of any legislation to deal with this crisis. Unfortunately, the far left objected, and he’s since wobbled,” Senate Minority Leader Mitch McConnell (R-KY) said Wednesday. “That’s led to top Democrats in Congress balking at even the most modest of reforms. They now seem to prefer a blank check that would preserve the status quo instead.”

As Congress dithers on border crisis legislation, the lives and prospects of tens of thousands of children fleeing violence and poverty in Central America hang in the balance.