With Conan O’Brien about to change the calculus of late-night cable programming, the Comedy Central channel has made a move to lock up its two dominant stars, Jon Stewart and Stephen Colbert.

The network has signed both hosts — they each attract more young viewers than even the late-night shows on the broadcast networks — to new contracts that will keep them in the 11 p.m. and 11:30 p.m. weeknight slots through the next presidential election in 2012.

“That’s a big deal for us,” said Doug Herzog, the president of the MTV Networks Entertainment Group, which includes Comedy Central. “For us, election years are like Olympic years.” The two politically oriented comedy shows hosted by the two stars — “The Daily Show” with Mr. Stewart and “The Colbert Report” with Mr. Colbert — have both seen big ratings bumps in presidential election years, Mr. Herzog said, “and some of that carries over each time, so we keep going up.”

The timing of the new deal was not directly related to the impending arrival in November of Mr. O’Brien, the former NBC late-night star, on the cable channel TBS — but Mr. Herzog noted that his comedy channel could hardly be unaware of it.