When Congress returns to Washington after the Labor Day recess, it will immediately face a significant budget crisis.
That's because funding for this year's budget will expire at the end of September and neither the House nor the Senate have passed a comprehensive spending bill for the fiscal year that begins on October first.
The most likely course of action is that Congress will pass what's known as a "continuing resolution" to maintain current spending levels for several months. If that happens, President Trump is demanding that the legislation also include money to construct a wall along the U.S. border with Mexico.
Trump says he won't sign a continuing resolution that does not include the money for the border wall and will shut the federal government down instead.
Sen. Patrick Leahy is the ranking Democrat on the Senate Appropriations committee.
"I cannot think of anything so juvenile as to suggest closing down the government if you can't have a wall, that was from his campaign promise, a wall that Mexico will never pay for,” said Leahy. “It costs a billion and a half dollars to two billion dollars a day to shut down the government."
Sen. Bernie Sanders doesn't think that many of his GOP Senate colleagues will support the president on this issue.
"I think this president is politically isolating himself, not just from the American people, not just from Democrats, not just from independents, but from more and more people in the Republican Party as well," said Sanders.
When the issue comes to a head in several weeks, Sanders doesn't believe that Trump will actually follow through with his threat.
"I think the overwhelming sentiment in this country is that building a wall would be a huge waste of money,” said Sanders. “The idea of crashing the federal government over this issue is totally absurd, between you and me I don't think that's going to happen."
Rep. Peter Welch says he supports efforts to strengthen border security through the use of drones and other electronic surveillance but he says the construction of a wall is not an effective strategy. Welch says shutting the federal government down over this issue could have dire consequences.
"When he is threatening to shut the government down, maybe default on our debt in order politically to get his way on another topic, he's putting at risk the financial well-being of the people of this county," said Welch.
Welch thinks Trump is playing to his political base by insisting that the wall be built.
"This wall that's a fixation for him has less to do with border security and a lot more to do with the politics of immigration which he's whipping up instead of solving," said Welch.
Sen. Leahy says he has a simple solution to avert this crisis but he doubts the president will use his approach.
"If he wants to ask the Republican-controlled House and Senate to have an up or down vote on his wall, he 'ought to do that. But he knows that the Republicans are not going to give him a majority vote for that wall because it just makes no sense," said Leahy.
While many House Republicans appear to support efforts to include funding for the wall in a temporary spending bill, a number of Senate Republicans have voiced their strong concern with this approach.