Public opinion polling showed him facing his first credible challenge since defeating Heckler in 1982.

Indeed, there has been no credible scientific challenge to the idea that evolution, the foundation of modern biology, explains the diversity of life on earth.

Weaver gave Lewis his first credible challenge in a decade, holding him to only 55 percent of the vote.

There is no credible scientific challenge to the theory of evolution as an explanation for the diversity and complexity of life on earth.

It is the foundation of biological science, with no credible challenges within the scientific community.

Stork raised more than $1 million from over 9000 contributors, and was poised to give Shaw only his third credible challenge ever.

Johnson faced a credible challenge from state Senator Chris Murphy.

He didn't face a credible challenge again until 1970, when former Johnson administration official Jim Jones held him to only 55 percent of the vote.

He said the Democrats' challenge on his residency "was designed not to be a credible challenge to my candidacy."

At last, for the first time since the 1980s, an American president had issued a credible challenge to those who promote evil around the world.