The Senate voted down four measures Monday evening relating to gun measures after hearing debate from both Republican and Democratic senators. The vote comes one week after a gunman opened fire in an Orlando nightclub, killing 49 people before being killed by police. (Reuters)

Update No. 2: All four measures, as expected, failed

Update: A new poll from CNN shows 92 percent of Americans support expanded background checks and 85 percent support preventing those on terror watch lists from buying guns. As we'll explain in the post below, though, none of the below proposals aimed at these things are likely to pass.

One filibuster, two gun control proposals, four party-line votes, zero compromises, lots of finger pointing.

That's what we can expect Monday evening as the U.S. Senate votes on four different gun control amendments -- two offered by Republicans, two by Democrats -- a week after the deadliest mass shooting in U.S. history.

We can confidently predict all four of these votes will go nowhere because the Senate took almost the exact same votes in December after the San Bernardino, Calif., attacks. Those votes largely fell -- and failed -- along party lines, with Republicans supporting looser versions of gun control proposals and Democrats supporting stricter versions.

We have no reason to expect different results Monday. Still, all is not lost: Both sides can and probably will use the results of Monday's votes to rally their bases for November and try and apply pressure to the other side over the next few weeks and months.

Here's a step-by-step guide on what Monday's gun control votes mean and how to follow along.

The ground rules: The votes are expected to start at 5:30 p.m. Eastern time on Monday, and they'll be proposed as amendments to a larger spending bill for the Commerce and Justice departments.

All four amendments will need 60 votes to be included in the package, which will also need to gain final approval. But given the partisan makeup of the Senate (54 Republican, 46 Democrat), and how the gun debate tends to fall neatly along partisan lines, we don't expect any of the proposals to advance.

No. 1: Tighten up our background check system (Republican amendment)


(AP Photo/J. Scott Applewhite)

What it proposes: Tries to open the lines of communication between the background check agency that Congress set up in the 1990s, the federal courts, the states and Congress to better carry out background checks. More specifically, defines what it means to be found "mentally incompetent" to buy a gun. Also requires the attorney general to conduct a study on "various sources and causes of mass shootings, including psychological factors, the impact of violent video games, and other factors."

Sponsor: Sen. Chuck Grassley (R-Iowa), chair of the Judiciary Committee

Amendment name to follow along on C-SPAN: S. Amdt 4751

How this fared in previous votes: Not well. A version of this that Grassley introduced in December failed to clear the 60-vote hurdle, 53-46.

Our prediction: It will fail this time too. Democrats don't think it does enough to expand background checks because, well, it doesn't expand background checks. It simply tries to improve the system we have now.

No. 2: Expand background checks (Democratic amendment)

The Fix's Amber Phillips breaks down why Congress is unlikely to pass major gun control legislation, despite Sen. Chris Murphy (D-Conn.) filibustering for 15 hours on June 15. (Peter Stevenson/The Washington Post)

What it does: Requires that a federal background check be conducted before every gun sale in the U.S., period. (The background check system Congress set up in the '90s only requires background checks by federally licensed firearm dealers, which means you can usually skip it if you try to buy a gun online from a private dealer, at a gun show or from your friend.)

Sponsor: Sen. Chris Murphy (D-Conn.), the senator who talked on the floor for nearly 15 hours Wednesday to demand these votes. (For what it's worth, Senate Republicans say that even before Murphy seized the Senate floor, they expected Democrats to force votes on gun control amendments.)

Amendment name to follow along on C-SPAN: S. Amdt 4750

How this fared in previous votes: Not well, although it got some bipartisan support. It failed to get the 60 needed to move on, 48-50, although four Republicans voted for it: Mark Kirk of Illinois, Susan Collins of Maine, John McCain of Arizona and Pat Toomey of Pennsylvania.

Our prediction: It will fail again. Most Republicans don't support expanding background checks to gun shows and other purchases -- or simply fear any additional gun laws are a slippery slope.

No. 3: Prevent suspected terrorists from buying guns (Republican version)

The FBI's Terrorist Watchlist reportedly had over 800,000 names on it in 2014. Omar Mateen, who killed 49 people at an Orlando nightclub June 12, was once one of those names. Here's what you need to know about the Watchlist. (Monica Akhtar/The Washington Post)

What it does: Right now, anyone on the FBI's various terrorist watch lists -- including the no-fly list that prevents you from getting on a plane -- can legally buy a gun. Under this bill, if you're on that list and try to buy a gun, you'd have to wait 72 hours. The idea is to give federal officials time to convince a judge there's probable cause you have ties to terrorism while still protecting the 2nd Amendment rights of anyone who is mistakenly on a terrorist watch list -- like the late Sen. Ted Kennedy (D-Mass.) once was.

Sponsor: Sen. John Cornyn (R-Tex.), Senate Republicans' No. 2 leader

Amendment name to follow along on C-SPAN: S. Amdt 4749

How this fared in previous votes: Not well. (Sensing a trend here?) A similar version failed in December on a 55-44 vote. Democrats -- and Attorney General Loretta Lynch -- say it's impossible to put together a case that a potential gun purchaser is a suspected terrorist in just three days, so they argue this bill would essentially allow anyone on the watch list to still be able to buy a gun.

Our prediction: It will fail again, for the reasons described above.

No. 4: Prevent suspected terrorists from buying guns (Democratic version)


Sen. Dianne Feinstein (D-Calif.) (Chip Somodevilla/Getty Images)

What it does: Lets the attorney general ban anyone on FBI's various terrorist watch lists from being able to buy guns. If you feel like you're mistakenly on the list and you get denied a gun, you can challenge the FBI's decision in court.

Sponsor: Sen. Dianne Feinstein (D-Calif.)

Amendment name to follow along on C-SPAN: S. Amdt. 4720

How this fared in previous votes: Not well, although it got some bipartisan support. A similar version of this failed in December, 45-54, with two senators voting on the other side: Sen. Heidi Heitkamp (D-N.D.) voted with Republicans against this bill, and Sen. Mark Kirk (R-Ill.) voted with Democrats for this bill.

Our prediction: It will fail again. Republicans think this bill takes away people's constitutional rights for due process because it bans them from buying a gun first, then allows them to challenge it in court later. And even as some Republicans have expressed a willingness to look at the no-fly list proposal -- up to and including Donald Trump -- they are more likely to favor the GOP proposal over this one.

Some potential areas of compromise

Believe it or not, there are some opportunities -- however small -- for Congress to move forward on gun control legislation in the wake of Orlando.

For example, here's one new idea that almost all of the four proposals above, have added: If a person who has been on one of the FBI's terrorist watch lists at any point in the past five years tries to buy a gun, the federal government must immediately notify law enforcement about it. The Orlando shooter, Omar Mateen, had been on and off the FBI's watch list before he bought his weapons.

And there are negotiations going on behind the scenes to try to merge Democrats' and Republicans' terrorist watch list proposals. As The Washington Post's Karoun Demirjian reports, Collins (R-Maine) is working on something that Democrats haven't dismissed outright.

She wants to prevent people on two of the FBI's terrorist watch lists (it's unclear exactly many lists there are for perhaps obvious reasons) from buying guns: the no-fly list and the selectee list.

Both lists deal with a person's rights at the airport. If you're on the no-fly list, you can't board an airplane. If you're on the selectee list, you get extra security screening when you try to board a plane. Mateen was on the selectee list for a time. And under Collins's proposal, if you are on these lists and are denied your right to buy a gun, you can challenge it, and if you win, the government has to pay your legal costs.

Again, her proposals are not exactly what Democrats want (they don't like the idea of working with just these two terrorist watch lists) or what Republicans want (they don't like the idea of banning a person from buying a gun first, then offering legal recourse later). But that's the essence of a compromise, and right now it looks like the only one the Senate's got.

Tellingly, Collins's proposal isn't up for a vote Monday, suggesting it might not yet have backing from Republican leaders.

Who to follow on Twitter for Monday's votes

Definitely these knowledgeable congressional reporters and teams:

The Washington Post's Karoun Demirjian:

C-SPAN's Craig Caplan:

Fox News's Chad Pergram:

And CQ Roll Call's Bridget Bowman:

This post has been updated to more clearly reflect that you can circumvent a background check if you buy a gun online from a private sale (of which there are many) but not from a federally licensed firearms dealer selling firearms online.