The schedule is especially packed in New Hampshire, an early presidential nominating state where there is a competitive Senate race Democrats are flocking to this month.
Gov. Gavin Newsom of California taking the stage during a campaign event for Representative Chris Pappas, the Democratic Senate nominee, in Exeter, N.H., on Saturday.
Two major Republican super PACs are said to be withdrawing cash from the races of the incumbent Representatives Thomas H. Kean Jr. of New Jersey and Mariannette Miller-Meeks of Iowa in an effort to triage the midterm map.