Abortion is back in the center of American politics -- and it's not likely to go away anytime soon.

Senate Republicans held a vote Monday evening to defund Planned Parenthood by stripping $528 million in federal funds for the organization, whose officials were seen on clandestinely taped videos speaking casually about what to do with tissues of aborted fetuses. (Planned Parenthood officials have apologized for their tone but denied they discussed illegally selling fetal tissue for profit.)

The vote failed a procedural hurdle. And even if it had passed and also made it through the House, President Obama promised to veto it.

But unlike other political dramas that fade after a vote or two in Congress to satisfy outraged lawmakers and activists, the Planned Parenthood storm has the potential to gather oxygen and suck in everything around it -- up to and including this fall's debate to fund the government.

Here's a step-by-step look at how the Planned Parenthood debate could conceivably shut down the government:

Abortion becomes even more of a rallying cry among Republicans ...

... during Thursday's Republican presidential debates, which present a prime-time opportunity for Republicans to hammer on a time-tested and base-approved issue.

Expect the four senators running for president to each promise voters that they will lead the fight in Congress to make sure federal dollars never again go to such an organization.

On Monday, Republicans' top-tier candidate, Donald Trump, added fuel to the storm when he told Hugh Hewitt on Hewitt's radio show that he supports shutting down the government to defund Planned Parenthood, saying if Republicans can stick together, they can win this.

Antiabortion advocates demand another shot...

… at defunding Planned Parenthood and, sensing a renewed political will on the subject, Republican congressional leaders decide to give it to them.

When they return from their five-week August recess, Senate Majority Leader Mitch McConnell (Ky.) and House Speaker John A. Boehner (Ohio) figure the best way to win this fight is to attach a bill defunding Planned Parenthood to a must-pass bill that funds the government. This is basically what happened with defunding Obamacare -- an effort that failed after leading to a shutdown of more than two weeks.

Republicans gamble that Obama won't stop a bill to fund the entire government just to save Planned Parenthood, which also gets government funding from state and federal Medicaid dollars.

Democrats draw a red line, too.

Perhaps motivated by the political will within their own base, Democrats in Congress and the White House collectively decide that, yes, Planned Parenthood is worth fighting for. The organization provides crucial health-care services for women across the country, and federal funds are already banned from going to abortions in most cases, they say.

"It is our obligation to protect our wives, our sisters, our daughters and our granddaughters from the absurd policies of a Republican Party that has lost its moral compass," Senate Minority Leader Harry Reid (D-Nev.) said on the Senate floor Monday before the vote.

Senate Democratic leaders declare they will block any bill that defunds Planned Parenthood, even if that bill funds the government. They calculate that voters will blame Republicans for the shutdown, as polls show they did after the government shutdown over Obamacare.

"It’s clear that Republicans are saying shut down the government unless I get my way on an extraneous issue," said Sen. Charles E. Schumer (D-N.Y.), the party's next-in-line Senate leader. "And the American people are wise to that."

During the Obamacare debate, Republicans had a plurality of voters supporting their bid to defund the law.

But a Monmouth University Poll taken over the weekend shows they don't have that kind of public support -- at least not yet --for a Planned Parenthood fight. The poll found that about half of Americans are aware of the leaked videos, but less than half support defunding Planned Parenthood: About 4-in-10 Americans support defunding it. That gap narrows among registered voters -- 42 percent support defunding, while 47 percent don't.

The Sept. 30 deadline to pass a bill to fund the government comes and goes ...

... without a spending bill signed. Instead, the spending bill been dragged into the emotional and seemingly intractable abortion debate -- a debate that for decades has consumed both sides with equal passion and little movement.

The government shuts down.

And then … ?

We're not sure. If the government shuts down, both sides have incentives to dig in their heels and wait it out to get what they want.

The 2013 government shutdown ended when Republicans stood down from their demand to defund the health-care law -- but only when lawmakers were faced with another urgent deadline to raise the U.S.'s borrowing limit. The debt ceiling is not as immediate of a concern this time around, so it's unlikely to help force a deal.

Another factor: Democrats controlled the Senate back in 2013, so they had more leverage to use against House Republicans. Now, Republicans control both chambers of Congress, which means they might feel like they can hold out longer to win this fight. After all, the party needs only six moderate Senate Democrats to come to their side to override Obama's veto. (In Monday's vote, two Democrats -- Indiana's Joe Donnelly and West Virginia's Joe Manchin -- voted with Republicans, and Illinois Republican Mark Kirk voted with Democrats.)

How likely is this to play out?

Before the swirling abortion debate arrived at Washington's doorstep, Forbes columnist and congressional budget watcher Stan Collender puts the likelihood of a government shutdown at 40 percent. Now, he said, it's at 60 percent -- citing the Planned Parenthood situation.

The best way to predict the abortion-storm forecast? The more you see Planned Parenthood and abortion in the news this month, the likelier it is the government could shut down because of it.