Pence Is Trying to Control Republican Politics. Trump Aides Aren’t Happy.

Representative Jeb Hensarling of Texas needed a favor: Before retiring at the end of his term, Mr. Hensarling, a powerful conservative, wanted to anoint an activist named Bunni Pounds as his successor. He reached out to President Trump for help, but Mr. Trump and his aides hesitated to meddle in a House primary, according to a person familiar with the overture.

Instead, Mr. Hensarling found a willing ally at Mr. Trump’s right hand: Vice President Mike Pence. Anxious to please his former House colleague, the vice president backed Ms. Pounds last month in a tweet that blindsided key White House aides.

The eager assistance Mr. Pence provided a senior lawmaker reflected the outsized political portfolio that the vice president and his aides have seized for themselves as the 2018 elections approach. While Mr. Trump remains an overpowering personality in Republican politics, he is mostly uninterested in the mechanics of managing a political party. His team of advisers is riven with personal divisions and the White House has not yet crafted a strategy for the midterms. So Mr. Trump’s supremely disciplined running mate has stepped into the void.

Republican officials now see Mr. Pence as seeking to exercise expansive control over a political party ostensibly helmed by Mr. Trump, tending to his own allies and interests even when the president’s instincts lean in another direction.