President Barack Obama called on Republican and Democratic Congressional leaders on Tuesday to “act like grown-ups” and put aside their differences on a six-month spending bill.

In an impromptu news conference at the White House, Obama bluntly criticized the pace of talks and argued it is up to himself, Speaker John Boehner and Senate Majority Leader Harry Reid (D-Nev.) to quickly come to terms on a bill to avoid a government shutdown.

“There are some things that we can’t control. We can’t control earthquakes, we can’t control tsunamis, we can’t control uprisings on the other side of the world. What we can control is our capacity to have a reasoned, fair conversation between the parties and get the business of the American people done,” Obama said.

“And that’s what I expect,” he added.

Obama also rejected a one-week stopgap spending measure being pushed by House Republicans, saying he would only support a two- or three-day extension to allow negotiators to finish their work.

“We are now at the point where there’s no excuse to extend this further. If over the next 24 to 48 hours a deal is done and we just can’t get the paperwork through Congress quick enough, and they want to do a clean extension for two or three days in order to go ahead and complete a deal, then that’s something that we could support,” Obama told reporters.

“But what we’re not going to do is to once again put off something that should have gotten done several months ago.”

Boehner, who introduced the one-week bill late Monday, declined at his own news conference Tuesday to say whether he would support a shorter extension. “We will continue to assess where we are in the next few hours and next few days,” he said.

Boehner also issued his most emphatic rejection of a proposed six-month bill that would cut $33 billion in spending. Although negotiations have been based for days on a top-line reduction of $33 billion, the Ohio Republican ruled that level out Tuesday.

Democrats “like to insist that $33 billion is their top number and to use smoke and mirrors to get there. That is not acceptable to our members,” Boehner said.

Additionally, Boehner acknowledged that including a host of controversial policy riders in the final spending bill is as important to Republicans as is cutting spending. The riders were included in a House-passed spending bill that included $61 billion in cuts. That measure stalled in the Senate.

Reid rejected Boehner’s one-week proposal Tuesday.

“It’s really time to get the job done. Republicans need to stop clinging to a bill that has already been defeated in the Senate. That bill is a non-starter. They have trouble divorcing themselves from that ideologically driven H.R. 1. They’re having a lot of trouble doing that. But we know the bill is awful,” Reid said.