Texas Rep. Mike McCaul has emerged as a leading candidate in the White House’s search for a homeland security secretary, according to three people familiar with the conversations. The White House hasn’t rushed to fill the post — which was vacated in July when President Donald Trump tapped John Kelly, who was then serving as DHS secretary, as his chief of staff — but the hurricane that slammed Texas last month as well as the one expected to hit Florida in the coming days have given it increased urgency.