In his last year in office, President Obama is going no-holds-barred on gun control.

He has spent this entire week rolling out executive orders to enforce and tighten existing gun laws, he held a town hall Thursday night with CNN defending his actions, and he published a New York Times op-ed Thursday promising to throw his weight only behind candidates who support "common-sense gun reform."

"All of us need to demand leaders brave enough to stand up to the gun lobby’s lies," he said.

But the president's promise to hold candidates -- especially Democrats -- to the fire if they don't support gun control proposals is a largely hollow one. And that's because his support simply won't make much of a difference in upcoming elections.

There are a few reasons why. Let's break them down:

There aren't very many Democrats who Obama's threat would affect

To prove our point, let's look at the Senate, where most of the action in Congress on guns has been in the past few years. Almost all of the Senate Democrats who voted against measures Obama would likely consider "common sense" -- expanding background checks, banning assault weapons and high-capacity magazines -- aren't even up for reelection this year.

Senators Joe Donnelly (Ind.), Martin Heinrich (N.M.), Heidi Heitkamp (N.D.), Joe Manchin (W.Va.), Claire McCaskill (Mo.) and Jon Tester (Mont.) all voted with Republicans and against Democrats on at least one of nine gun amendments the Senate debated in April 2013, four months after the carnage in Newtown, Conn.These senators are all up for reelection in 2018. (McCaskill's office points out that while she voted with Republicans on some amendments like this one, she didn't vote against any gun control measures Obama explicitly supported.)

Senators Mark Warner (Va.) and Tom Udall (N.M.) voted with Republicans back in 2013 on some gun measures, but they aren't up for reelection until 2020.

The only Senate Democrat who Obama's threat might apply to this year would be Sen. Michael Bennet (Colo.), who voted in 2013 against banning so-called assault weapons. Bennet is Senate Democrats' only vulnerable incumbent on the ballot in November; he's up for reelection in a purple swing state, and his colleague, former senator Mark Udall (Colo.) lost his reelection in 2014.

But Bennet has voted with gun-control supporters on nearly everything else since, including votes the day after the San Bernardino, Calif., mass shooting to expand background checks and block people on the government's no-fly list from getting guns.

And it's tough to see Obama carrying through on his threat for one Senate Democrat who took one anti-gun-control vote three years ago.

Pro-gun Democrats probably don't want Obama on their side anyway

So let's assume 2016 is a wash. And let's assume Obama keeps this promise come 2018, when more vulnerable Senate Democrats are on the ballot. At that point, it's a valid question to wonder whether these lawmakers even want the former president campaigning for them.

The 2018 midterms already look to be very difficult for Senate Democrats. They have to defend 25 seats, compared to eight for Republicans, which is essentially the 2016 election in reverse. At least five of those seats will be in red states where Obama isn't very popular.

Heitkamp, for example, is currently the only Democrat in the Senate still on-record opposing expanding background checks. She'll be running in a state that has voted for the Republican presidential candidate in the last 10 elections. It's doubtful she'll want Obama by her side then, and she told Politico's Burgess Everett and Lauren French she has "serious concerns" about Obama's unilateral actions on guns.

Tester, who is leading Senate Democrats' campaign arm, will also likely be in a tough spot in 2018. He'll be defending a seat in Montana, which handily went for Mitt Romney in 2012.

He told Politico he'll support Obama's executive actions so long as they don't “infringe on our 2nd Amendment rights or erode our Western values."

In other words, it sounds like Tester and Heitkamp are more concerned about appealing to gun-rights supporters in their home states than about having Obama help them out after his presidency is over.

Moving beyond the Senate for a moment here, there are certainly some more pro-gun Democrats in the House. But again, you have to ask yourself whether Obama would even campaign for House candidates -- and whether those in swing districts (who tend to be more pro-gun) really want a president with middling popularity numbers to help them out. We're guessing they're not losing sleep over the prospect.

Maybe his proposal is about someone else

Since Obama's threat rings so hollow on the congressional campaign trail, it's fair to wonder whether he was really speaking beyond them: to Democrats on the presidential campaign trail. And more specifically, the woman he hopes will succeed him in the White House.

We've argued on The Fix before that Hillary Clinton is the party's newest standard-bearer on guns and that, even before this campaign, she had a pretty solid gun control record. She supported background checks and banning assault weapons as a first lady and senator from New York. She's since become even more vocal on the issue, regularly mentioning taking on the National Rifle Association in her stump speech and in debates.

But Clinton did appeal to gun rights supporters during her 2008 primary with Obama, back when Obama was caught on tape talking dismissively about people who "cling" to guns and religion. And perhaps Obama is simply trying to make sure this issue remains a top priority for Clinton after the Democratic primary campaign is over.

After all, it's not out of the realm of possibility she shifts back toward the center of this divisive issue in the general election. That tends to be what happens in the general election.

But more likely than not, his campaign promise is more rhetoric than anything else

What's most likely is that Obama was using this op-ed as a messaging strategy to reaffirm his commitment to gun control -- and urge governors and lawmakers at the state level, where the real battle on guns will be waged this year, to do the same.

Either way, we've spent almost 1,000 words trying to figure out how his promise to make guns his litmus-test campaign issue will change electoral politics in any notable way. And if you've read this far, you can tell we've come up with the answer: probably not.