ROLL CALL: Bernie Sanders as GOP Tool: Their Plan to Use Him Against Democrats.

Sen. Bernard Sanders’ surprisingly strong candidacy for president has laid bare a sharp division within the Democratic coalition, pitting its activist base against the moderate-minded establishment.

It’s a split Republicans — especially the ones focused on winning down-ballot races this fall — are now racing to exploit.

The GOP is betting that the ideological fight at the top of the Democratic ticket will filter down the ballot, exposing incumbents and establishment-favored candidates to thorny questions about their support — or lack thereof — of the self-described socialist and his polarizing agenda. The idea: Either candidates disavow support for the Vermont senator and alienate supposed progressive allies, or they embrace Sanders and suffer the consequences in November when Republicans tie them to politically problematic issues such as single-payer health care. In effect, it mirrors the approach Democrats have taken in recent presidential elections, when they have successfully tied Republican candidates to the sometimes damaging positions of their party’s standard-bearer.

The strategy has special resonance now, after Sanders’s unexpectedly strong second-place showing in the Iowa caucuses. And for a party whose candidates have been relentlessly pressed for months about Donald Trump, there’s a palpable sense of relief and delight in giving Democrats a presidential headache of their own — one they hope lasts beyond even Sanders’s White House bid.

The Democrats’ problems have been underplayed.