A feud between Pennsylvania's establishment Republicans and the party's anti-establishment conservatives is exploding into the public.

It's happening at a sensitive time for Republicans who control Harrisburg.

Last month, House Speaker Sam Smith penned a public letter chastising Citizens Alliance of Pennsylvania, a political group that attacks Republican lawmakers who its leaders view as insufficiently dedicated to a small-government agenda.

This month, party leaders are in an airwave fight to try to prevent a key financial supporter of Citizens Alliance from winning a York County Senate seat in a March 18 special election.

Leo Knepper of Citizens Alliance says establishment Republicans are feeling the pressure.

The fight arrives as Gov. Tom Corbett faces lackluster public approval ratings and Senate Republicans are trying to protect their narrowest majority in two decades.