President Obama and Texas Gov. Rick Perry will meet on Wednesday to talk about the humanitarian emergency at the U.S.-Mexico border, but the real fireworks are likely to be on Capitol Hill, where Democrats and Republicans will begin working on the president’s $3.7 billion funding request for emergency operations to deal with the crisis.

Although leaders of both parties officially reserved judgment when the White House released its proposal Tuesday, rank and file members, as well as senior staffers, indicated that the money will be all but impossible to pass though the current Congress, despite the fact that nearly all are in agreement that the situation for the nearly 100,000 children in custody from California to Texas is nothing short of dire.

Of the $3.7 billion requested, nearly half, $1.8 billion, would be set aside for the Department of Health and Human Services to house and care for the waves of immigrant children already in U.S. custody. Slightly less, $1.4 billion, would go to border security measures like drones, border agents, immigration judges to speed the processing time for asylum hearings, and returning the children to their countries.

In its request, the White House painted a bleak picture of a federal workforce so pressed by the crisis that, without more money from Congress, "Border Patrol agents will have to be re-assigned to child care duties from their border security work."

But major sticking points quickly emerged among lawmakers before the White House even sent its proposal Tuesday morning, including an insistence by many Republicans that the new spending be paid for with cuts elsewhere in the federal budget, an idea that White House Press Secretary Josh Earnest rejected out of hand Tuesday.

“The answer is that this is an emergency supplemental funding request and with an emergency request like this, traditionally, Congress has not sought to bog down that process in the search for offsets,” he said.

Beyond the accounting of the funds, Democrats in the House and Senate preemptively raised the concern that the emergency money not be tied to policy riders, especially any changes to the 2008 law that currently gives extra protections to minor children coming to the United States from countries other than Mexico and Canada. Republicans and the White House have pointed to the law as a legal impediment to quickly sending the detained children back to their home countries. On Tuesday, the White House angered many Democrats by saying that in addition to the funding request, the president is also asking that Congress pass a bill changing portions of that law. “If they make it a straight funding bill, you could see some success. But if you have the due process of those young unaccompanied kids stripped out, it’s going to become very messy very quickly,” said a senior Democratic aide. “This is a humanitarian and refugee crisis, but the Republicans want it to be about immigration reform.” Other objections came on the Republican side where the phrase “blank check” popped up again and again, including from Sen. John Cornyn, who went to the Senate floor to take Obama to task for not going to the border this week during his Texas fundraising swing. ”I have no doubt that some pieces of [the emergency funding] are justified,” Cornyn said, adding that Obama needs to visit the border region. “Only then will we be ready to work through this request the president has sent us and figure out how to solve this problem.”Rep. Tom Cole from Oklahoma, a close ally to House Speaker John Boehner, said he won’t commit to vote for the funding without more details on border security. “If the money is to fix the problem, yes. But if it is simply to facilitate the flow, no,” he said on MSNBC’s Daily Rundown. “We’ll see what’s in it. I don’t think a $2 billion check is the answer.” More potentially problematic for the administration was a sort of proxy war over comprehensive immigration reform that Republicans seemed to graft onto the border crisis debate, with the familiar refrain that President Obama must first “secure the borders” before any discussion is made of admitting more immigrants to the country legally. Rep. Jim Bridenstine, a Naval Reserve pilot who flew drug interdiction flights over Central America before joining Congress, accused the president of causing lawlessness on the border and inviting mass illegal migration into the country with his 2012 executive order to grant a stay from deportation for about 600,000 illegal immigrants brought to the United States as children.

“Now the president wants our constituents to pay $3.7 billion for a problem he created?” Bridenstine said, becoming one of several advance “no” votes on the legislation without changes. “Without a secure border, this is just the beginning.”

With the president squarely between the rock of Republican resistance to his immigration policies and Democrats’ insistence that the White House not move to deport tens of thousands of migrant children without due process, Josh Earnest indicated no Plan B exists if Congress cannot find a compromise to pass Obama’s nearly $4 billion emergency funding request.

“If you take Democrats and Republicans on Capitol Hill at face value, you would expect their actions to back up their rhetoric,” Earnest said. “And their rhetoric indicates that this is a pressing situation that needs to be dealt with immediately. It will be up to Congress to do that.”