TULSA, Oklahoma - Democrats running for the U.S. Senate seat vacated by Sen. Tom Coburn have a lot of voters to convince.

A News 9/News On 6 poll indicates 76.3 percent of likely Democrat voters are undecided, six weeks before the June 24 primary election.

The poll shows 9.4 percent favor Midwest City resident Jim Rogers, 9.2 percent prefer state Sen. Connie Johnson and five percent support Anadarko resident Patrick Michael Hayes.

"The Democrats right now are suffering for a lack of engagement," said Bill Shapard, CEO of SoonerPoll.com. "[Conservative Democrats] are more or less thinking, 'I'm not going to vote or I may vote for the Republican,' and that's the reason why we have a lot of Republicans win in a state that's still dominated by Democrat registration."

One Democrat will have to get more than 50 percent of the votes cast in the primary to avoid a runoff with the closest opponent. The Democrat winner will meet a Republican and Independent challenger in the Nov. 4 general election.

SoonerPoll conducted the survey of 631 likely Democrat voters between May 5 and May 10. Respondents were selected at random using landlines and cell phones. Results were weighted by gender, age, cell phone/landline collection and Congressional district, then stratified using a model of previous primary elections. The poll has a margin of error of plus or minus 3.90 percentage points.