Right before the candidate filing period opened on Tuesday, state Rep. Rex Rice (R) started airing the first ad of the race for the open 3rd district seat.

His 30-second spot, which stresses the candidate’s conservatism, started running Monday on the Fox News cable channel.

The ad buy was about $16,000.

Rice’s campaign spokesman, Trent Acker, said the campaign intends to stay on the air until the June 8 primary.

Rice’s leading rival for the Republican nomination, state Rep. Jeff Duncan, has not begun advertising yet, spokesman Allen Klump said.

Duncan has the endorsement of the anti-tax group Club for Growth.

The 3rd district is a Republican stronghold where the GOP primary effectively will decide who will replace Rep. Gresham Barrett (R), who is running for governor.

Rice and Duncan are the frontrunners in the primary, but the crowded contest probably won’t be decided until a June 22 runoff.