The group, the Conservative Victory Project, is intended to counter other organizations that have helped defeat establishment Republican candidates over the last two election cycles. It is the most robust attempt yet by Republicans to impose a new sense of discipline on the party, particularly in primary races.

“There is a broad concern about having blown a significant number of races because the wrong candidates were selected,” said Steven J. Law, the president of American Crossroads, the “super PAC” creating the new project. “We don’t view ourselves as being in the incumbent protection business, but we want to pick the most conservative candidate who can win.”…

The group’s plans, which were outlined for the first time last week in an interview with Mr. Law, call for hard-edge campaign tactics, including television advertising, against candidates whom party leaders see as unelectable and a drag on the efforts to win the Senate. Mr. Law cited Iowa as an example and said Republicans could no longer be squeamish about intervening in primary fights.

“We’re concerned about Steve King’s Todd Akin problem,” Mr. Law said. “This is an example of candidate discipline and how it would play in a general election. All of the things he’s said are going to be hung around his neck.”