No Senate leader had lost a primary challenge since 1964.

It would have been great to see Obama go through a primary challenge.

Making sure that each neighborhood has access to all the commodities it needs is the primary challenge.

His party could become angry enough to mount a primary challenge.

If he faces a primary challenge, it is likely to come from a more conservative candidate.

In fact, that figure is now below 1 percent, and it represents the primary challenge to Murphy.

She survived a primary challenge but lost the general election.

Researchers report that the primary challenge is getting people to use condoms all the time.

But is he hurt enough to generate a real primary challenge in 1996?

The other primary challenge could come from the plant itself; it has not operated for more than a year.