His hopes for facing Don Blankenship, the former coal executive and convicted criminal, were dashed on Tuesday when Attorney General Patrick Morrisey claimed the Republican nomination. Mr. Blankenship, who during the primary attacked Senator Mitch McConnell’s family in racially charged language, would likely have been abandoned by Senate Republicans had he won the nomination. And he may have been unelectable by general election voters.

[Read about Don Blankenship’s loss to Patrick Morrisey here.]

Mr. Morrisey, who first made his name by suing the Obama administration, will enjoy the full support and financing of the national party.

Also worrisome for Mr. Manchin were the number of Democratic voters who supported his primary opponent, who ran a nominal campaign. He lost about 30 percent of the vote and did even worse in some of the state’s coal counties, which are full of the sort of ancestral Democrats he will need to hold onto in November.

Interventions work

National Republicans and Democrats waded into the West Virginia Senate primary, and they found that interventions can be effective. First, a Republican group backed by Mr. McConnell’s allies spent heavily attacking Mr. Blankenship. Then President Trump issued a tweet on Monday warning West Virginia Republicans that Mr. Blankenship “can’t win the General Election in your State.”

Voters seemed to listen: The controversial coal baron finished third in what was largely a three-person race, taking just 20 percent of the vote.

Less immediately consequential, but still significant, was the role Democrats played in the state’s Republican primary, as a liberal super PAC linked to Washington strategists aggressively attacked Representative Jenkins. They feared that the Democrat-turned-Republican with a base in the state’s coal counties would be the strongest candidate against Mr. Manchin, and they wound up helping lift Mr. Morrisey to the nomination.