Rep. James Lankford headed into the final three weeks of the Oklahoma Republican Senate primary with more than double the cash on hand of his top opponent, state Speaker T.W. Shannon.  

Shannon and Lankford are locked in a tight battle to succeed Republican Sen. Tom Coburn, who is resigning at the end of this Congress. The winner of the June 24 primary — or Aug. 26 runoff — will be heavily favored in the November special election to serve out the remaining two years of Coburn’s term.  

According to pre-primary reports filed last week with the Federal Election Commission, Lankford had $732,000 in cash on hand as of June 4, while Shannon had $330,000. The two candidates’ fundraising totals in the pre-primary period, which covers April 1 through June 4, were closer. Lankford  raised $847,000 and Shannon brought in $626,000. Lankford also outspent Shannon over that two-month period, spending $1.1 million to Shannon’s $798,000.  

Lankford was the beneficiary of contributions from several congressional colleagues. Reps. Larry Bucshon, R-Ind.; Jeff Fortenberry, R-Neb.; Pat Tiberi, R-Ohio; and Reid Ribble, R-Wis., plus retiring Sen. Saxby Chambliss, R-Ga., all donated to Lankford through their campaign committees or leadership PACs.  

The only member of Congress to give money to Shannon was Texas Sen. Ted Cruz, who contributed through his Jobs, Growth and Freedom Fund leadership PAC. Cruz has publicly endorsed Shannon and campaigned for him in the state.  

Shannon, an enrolled member of the Chickasaw Nation, also received donations from a number of American Indian tribes around the country.  

The race is rated Safe Republican by the Rothenberg Political Report/Roll Call.