WASHINGTON—Defense Secretary Pete Hegseth has avoided impeachment for now. Democrats are pointing fingers at each other over how it happened.Republican leaders’ push to block the impeachment process passed 211 to 204 in the GOP-run House late Tuesday. Republicans stayed united—except for impeachment instigator Rep. Thomas Massie (R., Ky.)—and only a handful missed the vote, despite fears that their midterm-election drubbing last week would dent their column. But on the Democratic side, 11 members weren’t present for the roll call—potentially more than enough to have swung the result their way, angering activists and bewildering colleagues who wanted to maintain the pressure...