The 38-year-old entrepreneur has maintained a grueling schedule, but questions about the goals of his candidacy are mounting with less than two weeks before the caucuses.
The visit by the speaker and scores of House Republicans comes as the G.O.P. seeks to increase pressure on President Biden and Democrats to agree to severe new border policies.
The president will speak at Valley Forge on the anniversary of the Jan. 6 Capitol riot, and later at a South Carolina church where a white supremacist killed nine people.
It is the first state to give Robert F. Kennedy Jr., a noted vaccine skeptic who is running for president as an independent, a spot on its 2024 ballot.
The group, True the Vote, had been accused by the liberal organization Fair Fight of violating the Voting Rights Act by intimidating voters. A judge rejected the claims.
Her failure to mention slavery in response to a question about the causes of the Civil War has given Chris Christie fresh ammunition as they compete for the anti-Trump vote.