"A buck-and-a-half per gallon." That is the phrase that should now be on the lips of every Democrat, whenever they are interviewed about any subject. Because today we hit another grim milestone as the quagmire/stalemate with Iran continues with no end in sight.

As of this writing (the prices change almost hourly, now), the average nationwide price of a gallon of gasoline in America stands at $4.26 per gallon. At the start of this calendar year, in early January, that price was $2.75 per gallon. That means it has risen by $1.51 per gallon (basic math).

Most in the media don't fully encompass the scope of this rise correctly, because they are using the wrong baseline. They talk of the rise in the price of gas "since the war began," using the figure $2.94 per gallon as their starting point (note: all of these figures come from the GasBuddy website, although some in the media use numbers from AAA, which differ by a few pennies). But this ignores the fact that from the start of the year until the bombs actually began dropping, Donald Trump was threatening to launch a war against Iran, and the world oil markets reacted to this new possible risk by raising prices. So the real measurement should be from the low point before all the saber-rattling began in earnest, not just from the day before the war started. Eventually, the media types will catch up -- but not until the price of gas hits $4.44 per gallon (if it does go that high, that is). Until then, it is up to Democrats to make the case for using the lower baseline to figure the change.

It really is a potent political argument to make, because you can very easily contrast Trump's promises with the new reality we all face when filling our cars up. Here's how Democratic politicians should frame the issue:

Donald Trump campaigned with a promise that he would -- in his own words -- bring the price of gasoline down "by half" within his first year in office. So let's see how he did, shall we? The day he was sworn in, gasoline was selling for an average of about $3.10 across the country. Getting this down "by half" would mean a reduction of $1.55 per gallon. But gas prices never even came close to hitting $1.55 per gallon at any time during Trump's first year in office. In fact, for most of that year, they stayed exactly the same. Then, during the last few months of the year, prices actually did come down -- by a little over 10 percent. For people like the president who get easily confused by percentages, 10 percent does not equal "half." It just doesn't.

Then Trump started his war of choice with Iran. There was no imminent threat. Iran wasn't about to attack us or anybody else. But Trump decided it was the right time to pick a fight with them. He said it would only last "four or five weeks," but that turned out to be another lie. We're now in the third month of his pointless war, with absolutely no end in sight.

And I don't have to tell you what has happened to the price of gas. Instead of dropping by a dollar-fifty a gallon, since the start of the year the price has gone up by a buck-and-a-half per gallon. It's the exact opposite of what Trump promised, and even if the war magically ended tomorrow, we're all still going to be paying sky-high prices for a long time to come. In fact, it's nothing more than a war tax. It is a tax you pay every time you fill your car up, all because Trump wanted to go to war.

But you know what? Nobody voted to pay a buck-and-a-half more for every gallon of gas they have to buy. Nobody! That is not what Trump promised the voters at all, but it's what we all got instead.

That is the right way to frame it. Trump did exactly the opposite of what he promised he'd do, and we're all paying the price -- to the tune of a buck-and-a-half per gallon.

Trump is as politically weak as he has ever been during his second term, and Democrats should be feeding that growing discontent out there with every chance they get. One of the two big issues Trump ran on, after all, was the economy (the other was immigration). He swore he'd get all the prices back down starting "on Day One," and the voters believed him. He has been a massive disappointment on that front -- so much so that his numbers are now historically bad.

Reuters/Ipsos just released a new poll which showed Trump with a job approval rating close to 2-to-1 disapproval (34 percent approve to 64 percent who disapprove). But even that wasn't the most dismal number for him. The same poll showed Trump down a jaw-dropping 49 points on the issue of inflation. To put that into context, the worst showing Joe Biden had (even though inflation and gas prices were far higher during his term in office) was only 43 points underwater. Even more astonishingly (for those who remember the 1970s), Trump's rating is now below Jimmy Carter's worst rating, which was 46 points underwater.

Perhaps it is because Trump made such sweeping (and unrealistic) promises? Perhaps it is because everything he has done since he took office -- the tariffs, especially -- have resulted in higher prices for just about everything? Or perhaps it is because it is so obvious that gasoline prices have gone up a buck-and-a-half per gallon solely because of Trump's ill-conceived war? There are no external factors to the pain at the pump these days -- it's all due to Trump's war, period.

Whatever the reason, Trump seems to be completely blowing the chances for Republicans to survive the midterms. The number of seats lost in the midterms for the party in power usually directly corresponds to the president's approval ratings. And Trump's weren't in any great shape to begin with, but ever since the war began (and the prices at the pump skyrocketed), they've been sinking like a stone.

To their credit, Democrats have indeed been leaning in on the subject of the economy. They have highlighted high inflation, prices going up, and affordability in general. They are tapping into the public's discontent in a big way -- which is precisely what they should be doing right now. But now they have a new and potent way to frame their argument, which they should all be doing in unison.

Because gas now costs a buck-and-a-half more per gallon than it did in January. All due to Trump's war.

-- Chris Weigant

Follow Chris on Twitter: @ChrisWeigant