Going into Tuesday’s Oklahoma primary vote, former state Rep. Kevin Calvey led the field of Republicans jockeying to replace Rep. Mary Fallin (R-Okla.), who is leaving her Oklahoma City seat after two terms to run for governor.

Calvey, who ran for the GOP House nod in 2006, led in the SoonerPoll’s most recent survey with 27.8 percent support. Youth camp director James Lankford (R) was in second place with 19.9 percent, while state Rep. Mike Thompson (R), who has spent the most money of the top three candidates, was in third with support from 14.1 percent of respondents.

The July 7-9 phone survey of 309 likely GOP primary voters has a margin of error of 5.6 percent.

Calvey, who led the first SoonerPoll of the race in March, is expected to take the top spot in the race, but will likely face a runoff against either Lankford or Thompson. There are seven Republicans running for the nomination.

The race has primarily been a contest over which candidate is the most conservative. Oklahoma’s 5th district went for Sen. John McCain (R-Ariz.) in the 2008 presidential election by almost 20 points. 

Democrats Billy Coyle and Tom Guild are competing for their party’s nomination. 

The polls close at 8 p.m.