Mr. Jones is the only red-state Senate Democrat up for re-election in 2020. By taking on President Trump and the border wall, which are both popular in Alabama, and refusing to give ground on the shutdown, the senator may be the last “Doug Jones Democrat” to win here anytime soon.

Alabama has one of the largest groups of federal workers in the country, and the economic pain of those who are out of work because of the shutdown is rippling through local businesses across the state…

Mr. Jones’s opposition also underscores the challenge Mr. Trump faces in fulfilling one of his key campaign promises, and the fierce partisanship that has come to define the stalled shutdown negotiations. If the president can’t convince a Democrat from Alabama — the most vulnerable senator up for re-election in 2020 — to back his wall, who can he sway?