ALBUQUERQUE — The Republican Party was set to reaffirm support for President Trump in 2020, an unusual move that is quietly dividing GOP insiders between those anxious about possible primary challengers and others concerned about feeding a false narrative of vulnerability.

Resistance to Trump and noise about upending his renomination has motivated certain members of the Republican National Committee, the party’s governing body, to push a nonbinding resolution expressing the GOP’s commitment to the president in the 2020 primary, typically presumed for an incumbent. The RNC is expected to approve one of two proposals, or some combination, when it meets this week at a posh New Mexico resort for an annual business meeting.