Can openly biased or partisan journalists . . .

. . . engage in independent reporting and commentary -- as opposed to partisan propaganda? Here's some critical commentary from the conservative National Review Online within hours of John McCain selecting Sarah Palin as his running-mate in August 2008: 

          Ramesh Ponnuru: "Palin has been governor for about two minutes."

David Frum: "But question: If it were your decision, and you were putting your country first, would you put an untested small-town mayor a heartbeat away from the presidency?"

Shannen Coffin: "If John McCain has said that a year plus of statewide office (plus some small town politics) is good enough, why isn't state legislature and a couple of visits to the floor of the U.S. Senate?"

Jonah Goldberg: "Downside: She may not be ready for primetime. The heartbeat-from-the-presidency issue is a real one."

This isn't the drumbeat GOP cheer-leading one might get from a less independent source like Fox News at that crucial juncture.

More recently, NR devoted a whole issue (in Jan 2016) to opposing/exposing then-GOP-frontrunner Donald Trump.