In less than four days, the U.S. government could again be closed for business. Since 1976, the federal government has shut down 18 times, with the shutdown lasting three days or less during nine of those instances.
Two years ago, Obamacare was at the center of a partisan dispute that shuttered the federal government for 16 days. Now, it's a battle over a social issue—funding for Planned Parenthood—that could one again close federal offices and halt services if Congress fails to approve a budget by midnight on Wednesday.
"The last time we were here, it was because a group of conservative Republicans did not want to fund the Affordable Care Act," said Jared Bernstein of the Center on Budget and Policy Priorities, in an interview with CNBC.
In the current potential shutdown, Bernstein says "a similar group (of Republicans) wants to defund Planned Parenthood" and both Democrats and Republicans are trying to "figure out how leadership can work with this group of conservatives ... keep them satisfied and yet not close the government."
Still, others are sympathetic to the GOP's position. Recent videos about Planned Parenthood have emboldened the organization's opponents.
"A lot of Republicans are really up in arms," National Review Senior Editor Ramesh Ponnuru told CNBC.
Ponnuru, who is also a health policy analyst with the American Enterprise Institute, said that because "Planned Parenthood is the largest abortion provider in the country and also relies for most of its funding on the federal government, that does not sit well with pro-life conservatives."
According to Planned Parenthood's most recent report, $528.4 million dollars in federal funding provided 41 percent of the women's health organization's revenue.
Ponnuru says that a lot of pro-life Republicans "don't want to have a shutdown" because they don't think they "ultimately will succeed in having a shutdown cut off funding" for the nonprofit reproductive health organization. However, Ponnuru added, "there are other folks who want to have this fight."
On Thursday, in a 47-52 vote, the Senate rejected a short-term spending bill that would have defunded Planned Parenthood and funded the government until Dec. 11. The bill needed 60 votes to advance.