Republicans believe the Medicare for All slogan will alienate moderate voters in 2020.

But centrists warn that if he becomes the nominee his left-wing views could alienate moderate voters and hand Trump re-election.

Lobbyists said they feared a too-aggressive approach by Hensarling could backfire, leading to an extreme bill that would alienate moderate senators.

A long trial delay also could alienate moderate Republicans in the Senate who might support more extensive proceedings than McConnell seems to want.

Questions persist for both Sanders and Warren about whether their uncompromising liberalism may alienate moderate Democrats and independents whose votes are crucial to beat Trump.

They accuse the party of being too timid, too afraid of alienating moderate voters.

Most observers believed Bachmann's campaign to be gaffe-prone, while her extreme social views alienated moderate voters.

But she urged caution - focusing too narrowly on specific demographic groups risks alienating moderate Democrats.

But a hard line could alienate moderates and independents, whose support will be essential to election victory.

He said drawing conservative support while not alienating moderate lawmakers remained part of a "balancing act."

The Californian Republic Party has become fractured, splitting among Tea Party conservatives, anti-immigration activists, libertarians and an increasingly alienated moderate old guard.

Political scientist Staring said Harper's shift has risks, and he'll have to walk a fine line to hold his base without alienating moderates.

He said Trump's hard-right positions on issues such as immigration and gun control were alienating moderate suburban voters that his party needs to remain competitive.