DALLAS (AP) — Texas Attorney General Ken Paxton will be in an unfamiliar setting Monday night: heading his first campaign rally since the Republican announced his candidacy for the U.S. Senate 10 months ago. Paxton’s scheduled appearance is part of his stepped-up campaign to unseat four-term Republican Sen. John Cornyn and add a MAGA devotee to the Senate, a bid that has set up one of this year’s most contentious GOP primaries. Until Monday, Paxton waged a lower-wattage campaign, spent