Indeed, in 2006, she faced an aggressive primary challenge from Cynthia Tucker, a black medical professor.

But the Helms campaign, mindful that the issue would be used against the Senator, has mounted an aggressive challenge to the abortion rights position.

In other primates, the baring of teeth is usually an aggressive challenge.

Avoid staring directly into the dog's eyes, as this is likely to be interpreted by the animal as an aggressive challenge.

In battle, the South influences the brave, aggressive challenge of an opponent.

And it may prepare the way for even more aggressive challenges to come.

After skating to reelection from 1982 to 1990-including two completely unopposed bids in 1988 and 1990-he faced aggressive Democratic challenges for most of the 1990s.

Frimpong is well known for his aggressive challenges.

Several have fought off aggressive challenges from male opponents to win primaries.

If adopted, its change in standards will be among the most aggressive challenges in the nation to biology's bedrock theory.