With some fanfare, the National Republican Senatorial Committee has bought extremely early ad time in Michigan, a state where it has gone winless in Senate races since 2000, to pressure Sen. Debbie Stabenow (D). In the ad, a 2016 clip of Stabenow demanding hearings on Merrick Garland, President Barack Obama's final Supreme Court nominee, is contrasted with Senate Minority Leader Charles E. Schumer promising to impede the nomination of Supreme Court nominee Neil Gorsuch.

The lesson Democrats took from the slow-motion Garland debacle was that voters are not particularly moved by Supreme Court fights; partisans stay in their corners. But the idea that Stabenow, now seeking a fourth term, would feel pressure because Trump won Michigan needs some unpacking. So far, the five Democratic senators in states that voted for Barack Obama in 2012 then Donald Trump in 2016 are making absolutely no break from their party leadership. Stabenow, like Sen. Bill Nelson (D-Fla.), Sen. Tammy Baldwin (D-Wis.), Sen. Sherrod Brown (D-Ohio) and Sen. Robert P. Casey Jr. (D-Penn.), are instead behaving like partisan Democrats.

Talking to some Rust Belt Democrats this week, it's easy to see why:

1. Trade. It was a defining issue for longtime Democratic voters in Michigan, Pennsylvania, Ohio, and Wisconsin, the one that got them over their reservations to back Trump. Unlike Hillary Clinton — perhaps the last national Democratic candidate who can be identified with NAFTA, and possibly with the Trans-Pacific Partnership — the Democrats up for reelection in these states uniformly opposed the trade deal.

2. Betsy DeVos. In the Midwest especially, Trump has failed to take on an issue that wedges Democrats from the voters they need to win. With the nomination of Betsy DeVos for Secretary of Education, he's done the opposite, as Democrats have been bombarded by calls from anti-DeVos constituents and warned the rural voters who broke for Trump that DeVos is a threat to their public schools. One Democratic senator told me last week that he was honestly surprised to hear DeVos, in his office, making no attempt to finesse the rural schools issue — an approach that made it clear to him he could oppose her without obstruction. And in Michigan especially, the DeVos name has already been subjected to a political test, when Betsy's husband Dick DeVos self-funded a Republican campaign for governor in 2006. DeVos spent $35.5 million of his own money to lose by 14 points.

3. Mr. 46 Percent. In Stabenow's Michigan, and in Pennsylvania and Wisconsin, Democrats watched Trump grab their electoral votes while falling short of 50 percent of the popular vote. In each state, George W. Bush actually won a larger share of the vote in his 2004 reelection while losing them than Trump won while carrying them. In Michigan, Trump won 47.3 percent of the vote as almost six percent of voters picked third party candidates or left the top of the ballot blank. Twelve years earlier, Bush won 47.8 of the Michigan vote, losing narrowly but decisively to John Kerry.