Brock resigned his cabinet post in late 1987 to serve as the campaign manager for Senator Bob Dole's presidential campaign. Dole, the runner up to Vice President George Bush, was seen as a micro-manager who needed a strong personality like Brock to guide his campaign. Brock's late start in the Fall of 1987 left little time to help find an avenue to cut into Bush's substantial lead in national polls. Additionally, many viewed Brock as an imperious and inadequate manager who badly misspent campaign funds- largely on national headquarters staff- leaving Dole without adequate money for a Super Tuesday media buy. Dole and Brock had a public falling out, and Brock publicly fired two of Dole's favored consultants, ordering them off of the campaign plane. Dole dropped out of the race in late March 1988 after losing key primaries in New Hampshire, the South, and Illinois. Brock became a consultant in the Washington, D.C., area. By this point, he had become a legal resident of Maryland. In 1994 he won the Republican U.S. Senate primary in Maryland over future convict Ruthann Aron, but was soundly defeated (41%–59%) in the general election by Democratic incumbent Paul Sarbanes.