Larry Downing/Reuters
Speaker of the House John Boehner listens as U.S. President Barack Obama hosts a luncheon for bi-partisan Congressional leaders in the Old Family Dining Room at the White House in Washington, November 7, 2014.
Stan Collender, who has worked on both the House and Senate Budget Committees, now puts the odds of a shutdown at 60% - up from 40% last week. In his weekly running column on Forbes, he wrote that the uptick was due to the "craziness going on in Washington."
The federal government will shut down on Oct. 1 if Congress does not pass a spending bill to keep the government funded. And with the House of Representatives already in recess for the entire month of August, Congress only has 10 scheduled legislative days in September to figure out a solution.
Congressional Republicans and President Barack Obama had already been at impasse over spending levels for both military and domestic programs. But the introduction of a new, divisive issue is what led Collender to increase the odds of a shutdown.
"But the biggest change from last week in the odds of a government shutdown is because of the emergence of the one big thing that has been missing so far from the appropriations debate: a highly emotional, politically toxic and take-no-prisoners issue," he wrote.
"In the past that line-in-the-sand issue has been budget-related: the national debt, the federal deficit and taxes. This time it's the new GOP push to defund Planned Parenthood - a highly emotional social issue that has quickly become a political litmus test for Republicans."
Republicans seem ready to fight over the future of the women's health and family-planning organization Planned Parenthood, which has come under intense scrutiny after the release of undercover videos that show a Planned Parenthood executive discussing using aborted fetuses for research. Democrats have rallied to the organization's defense.
REUTERS/Jonathan Ernst John Zangas (L), who identified himself as a federal employee, and Janette Dunder (R) protest against the current government shutdown at the U.S. Capitol in Washington, October 2, 2013.
In the Senate, social conservatives are leading a push to attach a rider to the spending bill that eliminates more than $500 million in annual federal funding to the organization. And in the House, 18 conservatives have also told House Republican leadership that they will not support a bill to fund the government if it includes funding for Planned Parenthood.
The Senate is voting Monday on legislation that would defund the organization, in what's largely seen as a prelude to next month's debate.
The push to defund Planned Parenthood has been largely driven by the release of four controversial, undercover videos by the conservative Center for Medical Progress. The videos purport to show Planned Parenthood officials discussing the sale of fetal tissue.
"We expect a continuing resolution or another 'cromnibus' but note that the spending rhetoric remains contentious and a brief government shutdown is a distinct possibility," Isaac Boltansky and Alison Ashburn of the political risk firm Compass Point wrote in a recent note.