Many others in those states did not face a primary challenger.
He did not face a challenger in the general election.
The President, on the other hand, did not face a primary challenger this year.
For the first time since 1998, faced a Democratic challenger.
He faced a primary challenger, but won with over 70% of the vote.
Lewis did not face a Republican challenger in the primary election.
He is facing two challengers in the primary next month.
It is unlikely that she will face a major challenger in the Democratic primary.
If things are truly awful, he might even face a significant primary challenger.
Consequently, it is common that the candidate does not face a challenger.