Even if Congress beats the odds, and the government doesn't shut down come Oct. 1, Washington will probably still have undergone a lengthy, all-consuming debate about the issues that threaten to close its doors.

Which means if you follow Congress even a little bit -- or just happen to walk by a political rally, turn on the news, or log onto social media -- you're going to be hearing a lot about abortion, domestic and military spending, and highways.

So we tried to make it easy for you to to follow along. After all, nothing less than our government keeping its doors open is on the line.

Here's a quick explainer of the six issues that could cause a government shutdown.

Planned Parenthood

What you need to know about the ins and outs of Planned Parenthood, the controversy and what may happen next. (Gillian Brockell/The Washington Post)

The latest: Over the summer, an antiabortion advocacy group leaked videos of officials from the women's health provider talking in cavalier tones about fetal tissue. The videos, which would make anyone squeamish, rallied passions among antiabortion advocates everywhere, even though Planned Parenthood officials maintain they did nothing wrong (selling fetal tissue for profit is illegal; donating it to medical research, as Planned Parenthood says it does, is not). Republicans on the presidential campaign trail and in Congress subsequently called for the federal government to stop giving more than $500 million annually to Planned Parenthood -- even though those funds are prohibited from paying for abortions in most cases.

How it could cause a shutdown: Suddenly, abortion is back in the political debate in a big way. A group of Republicans want to pass a budget without funding for Planned Parenthood, but that's a major non-starter for Democrats, who have promised to hold up budget proceedings in the Senate until Planned Parenthood gets funded. President Obama has also said he'll veto any budget that doesn't have money for Planned Parenthood.

Major players: Republicans are pushing women to the forefront of this cause, including Sens. Joni Ernst (Iowa) and Deb Fischer (Neb.), and Reps. Diane Black (Tenn.) and Marsha Blackburn (Tenn.). But it's Rep. Mick Mulvaney (S.C.) in the House and Sen. Ted Cruz (Texas) in the Senate who are really leading the charge. Already, Mulvaney has 31 lawmakers on his side; enough to block a budget that doesn't defund Planned Parenthood.

The sequester

The latest: Most everyone in Washington agrees that the automatic spending cuts (a.k.a. the sequester) that were implemented after a 2012 budget debate need to be replaced with actual spending policy. But there are major sticking points between the White House and congressional Republicans over how much to spend on military and domestic programs. Democrats want equal increases to military and domestic spending, while Republicans just want to increase military spending.

How it could cause a shutdown: If House Speaker John Boehner (R-Ohio) can't get enough Republicans on board to pass a budget that funds Planned Parenthood, he'll need help from House Democrats to vote for it. Their price: A guarantee to negotiate in good faith about actual spending policy. If Boehner can't agree to that, he could be back at square one: facing a shutdown.

Major players: House Minority Leader Nancy Pelosi (D-Calif.) and Senate Democrats' No. 3, Sen. Chuck Schumer (N.Y.), seem to be the spokespeople for Democratic demands. Also watch Rep. Chris Van Hollen (Md.), the top Democrat on the House Budget Committee. 

A leadership challenge to Speaker Boehner

The latest: Rumors of leadership challenges are as old as Congress. Before the August recess, a soft-spoken, two-term Republican congressman from North Carolina surprised almost everybody and filed a symbolic motion to kick Boehner off his leadership post and force an election for a new speaker. Few took it seriously. But as the Planned Parenthood debate heated up in August, a group of antiabortion Republicans have since publicly promised to try to oust Boehner if they don't get what they want in budget negotiations.

How it could cause a shutdown: It ups the stakes, putting pressure on Boehner to make conservatives happy. As Steve Bell, the director of economic policy at the Bipartisan Policy Center and a former top Republican congressional budget aide, points out, Republicans who are publicly calling for a leadership challenge if Planned Parenthood doesn't get defunded are locking themselves into a leadership challenge -- one that if actually followed through would be extremely rare.

"A guy or a gal who says that publicly can't back down from it," he said.

Major players: Rep. Mark Meadows (R-N.C.) filed the initial challenge to Boehner. And Mulvaney -- the same one leading the Planned Parenthood debate -- is another to watch, along with fellow tea party leaders, such as Reps. Louie Gohmert (Tex.), Steve Scalise (La.), Steve King (Iowa) and Raul Labrador (Idaho).

The Iran deal

Rep. Matt Salmon (R-Ariz.) lambasts the international nuclear deal with Iran during a rally at the Capitol Sept. 9. (AP)

The latest: Thanks to a Herculean effort last week by Senate Democrats, President Obama's deal to rein Iran's nuclear program won't be derailed, even symbolically, by the Republican-controlled Congress. But that doesn't mean Republicans will let the issue lie. In the House, where the majority rules, Republicans voted three times on separate bills essentially rejecting the deal and implementing sanctions on Iran instead. Those bills likely won't pass the Senate and almost certainly won't be signed by Obama, but they demonstrate some Republicans' willingness to find another way to stop the Iran deal. 

How it could cause a shutdown: The Iran deal could end up being a negotiating chip in the budget debate much like Planned Parenthood. If there's enough will, opponents could try to cut off State Department funding to implement the deal, theorizes prominent budget analyst Stan Collender.

Major players: Rep. Peter Roskam (R-Ill.) led the charge in the House to vote on three separate bills disapproving of the Iran negotiations and could try to defund the deal in the budget.

The Export-Import Bank

On the Senate floor July 24, Sen. Ted Cruz (R-Tex.) accused "career politicians" of "looting the tax payer to benefit wealthy, powerful corporations." (AP)

The latest: Congress let this independent government agency expire in June. It was a big win for tea party Republicans, who criticized the bank for propping up large U.S. companies (such as Boeing) that are making risky-ish investments abroad.

How it could cause a shutdown: The debate over the bank is really about businesses' role in government, and for now those who want government out of the free market appear to have won. But bank supporters include Democrats and pro-business Republicans -- a potentially powerful alliance -- that could make the Export-Import Bank yet another sticking point in the budget debate.

Major players: On the anti-bank side, watch Cruz. On the pro-bank side, watch Sen. Lindsey Graham (R-S.C.), who represents a state where Boeing is a major employer. Both, of course, are running for president, too.

The Highway Trust Fund

Get caught up: The federal fund that helps pay for roads, bridges and rail projects has been bordering on bankruptcy for the past few years, in part because a national gas tax that fills it up hasn't caught up with inflation in two decades. Momentum is building in Congress for a long-term fix -- the Senate passed a six-year extension in July -- but lawmakers in both chambers can only seem to agree on the status quo.

How it could cause a shutdown: The trust fund is tied up with a number of potentially volatile debates. Within the Senate's plan to extend it for six more years (only three of which identify funding sources) is a measure to revive the Export-Import Bank. The fund also opens the door to a tax debate and a debate on federal government's role in paying for transportation projects. In short: Perfect shutdown material.

Major players: In the Senate, Sens. Barbara Boxer (D-Calif.) and Jim Inhofe (R-Oka.) negotiated the Highway Trust Fund extension. In the House, House Transportation Committee Chair Bill Shuster (R-Pa.) is leading negotiations.

What it looked like the last time the government shut down

WASHINGTON, DC - OCTOBER 07: Clouds fill the sky in front of the U.S. Capitol on October 7, 2013 in Washington, DC. Democrats and Republicans are still at a stalemate on funding for the federal government as the shut down goes into the seventh day. (Mark Wilson/Getty Images)