In the olden days, coal miners would carry caged canaries down into the mines to test for carbon monoxide . The idea was to detect a problem before it harmed humans.

This might serve as a useful metaphor for Republicans who still don’t know yet whether they won or lost a special election in coal country, but in which their candidate trailed by a few hundred votes Wednesday morning. The canary in the coal mine is on life-support. It’s time to get out while you can.

Democrat Conor Lamb’s strong showing against Republican Rick Saccone in Pennsylvania’s 18 th district is all the evidence you need to see the danger of being in the same party as Donald Trump on the mid-term ballot in November.

Why is this race such a dire warning sign? It’s not just because (a) Republicans spent a lot of money, or because (b) Trump visited the district as recently as Saturday, or because (c) Trump announced popular steel tariffs just before this election. Nor is it because (d) this district (that Trump won by 20 points!) should be favorable for Republicans (The other day, The Daily Beast’s Michael Tomasky did a terrific job of demonstrating that).

No, it’s because Pennsylvania-18 serves as one more data point—one more cautionary tale—about a much larger national trend. There are literally dozens of congressional districts that are more competitive than this one.

Whether you’re looking at a race like Virginia’s 2017 gubernatorial election or the Doug Jones’ recent upset in Alabama, the trend of Democratic enthusiasm is hard to deny. And in mid-term elections, enthusiasm is the thing to watch for.

“ To the degree Trump is popular, it isn’t transferable—and it certainly isn’t driving turnout. ”

Of course, compared to a presidential year voter turnout for special elections decreases on both sides. But since Trump won the presidency in November of 2016, in states as diverse as Kansas, South Carolina, Montana, and Georgia, Republican turnout has dropped precipitously compared to turnout in congressional races when Trump and Clinton were on the ballot.

As columnist Bill Scher noted after the recent Alabama special election where Democrat Doug Jones bested Republican Roy Moore, “ Compared with the 2016 presidential results, the Republican vote plummeted by 51 percent, while the Democratic vote ticked down by just 8 percent.”

Now, the truth is that it’s hard to compare what happened on Tuesday in PA-18 with what happened in November of 2016 because the long-time incumbent GOP Congressman, Tim Murphy, ran unopposed. Still, it’s clear now that Pennsylvania is the latest—and arguably, one of the most obvious—examples of this pattern.

To be sure, each race is unique, and campaigns do matter. The quality of the political candidates matter, too. It’s fair to say that in Pennsylvania, Democrats had a good candidate (not only was Lamb competent, but his moderate politics fit the district)—and Republicans didn’t.

Speaking of the importance of smart campaigns, an interesting aside is in order: Joe Trippi, who was Doug Jones’ top political advisor, was recently on my podcast. Trippi said that Trump’s visit to Pensacola, Florida, on the Friday before Election Day, gave Republican Roy Moore four-point boost. But it didn’t last. Jones’ internal tracking polls showed that it dissipated each day, and by Tuesday, Jones was ahead. What does this have to do with Pennsylvania? Donald Trump visited the district on Saturday night.

Maybe Trump should have traveled to the district on Monday instead?

Regardless, even if Saccone wins, it doesn’t change the trajectory of what is clearly becoming a horrible political environment for Republicans.

We have reached the “break glass in case of emergency moment.” The message is clear: Republicans must do whatever they have to do to survive the 2018 mid-term elections.

For many Republicans, step one will be to separate from Trump—and his abysmal approval ratings. Republican leadership, such as it exists, should cut them loose. What this means is that they should vote with the district, not with the party. And they shouldn’t feel compelled to defend the indefensible. In other words, be with Trump if and when it makes sense in your district, but don’t do so out of obligation. Localize the race as much as possible. Hugging Trump doesn’t seem to work. To the degree he is popular, it isn’t transferable—and it certainly isn’t driving turnout.

As conservative commentator Quin Hillyer noted, “ Trump endorsed Luther Strange. Strange lost. Trump endorsed Roy Moore. Moore lost. Trump endorsed Saccone, who appears to have lost. in 2016, Trump endorsed Renee Ellmers. Ellmers lost....”

Loyalty schmoyalty. Distance yourselves. Save yourselves. It’s every man for himself. Pennsylvania-18 is the canary in the coal mine. And there’s toxic gas flooding in!