The chairwoman of the Republican Party of Arizona defended an email on Friday in which she had said the party would stop Mark Kelly, a Democrat running for United States Senate, “dead in his tracks.”

Mr. Kelly is the husband of the former congresswoman Gabrielle Giffords, whom a gunman shot in the head in 2011 during a meeting she was hosting for constituents. Ms. Giffords, then a member of the House of Representatives, survived the attack, which killed six people and wounded a dozen others.

“Support the Republican Party of Arizona today and, together, we’ll stop gun-grabber Mark Kelly dead in his tracks,” the chairwoman, Kelli Ward, wrote Thursday in a fund-raising email, The Associated Press reported. The email also targeted Mr. Kelly’s platform supporting gun safety.

Given the backdrop of heightened attention to mass shootings — 53 people died in such attacks last month alone — and the episode in which Ms. Giffords was shot, Ms. Ward’s email drew criticism.