As we prepare to cast votes for a new U.S. Senator, replacing Tom Coburn, so-called "dark money" groups hope to influence your decision.
With less than a week before the primary, the question is who's paying for what when it comes to campaign finances.
James Lankford has raised and spent more money than T.W. Shannon.
According to Federal Election Commission filings, Lankford's brought in 2.1 million dollars and Shannon, 1.4 million.
But hundreds of thousands of dollars in outside money is pouring into this election, from groups not directly associated with their campaigns, hoping to influence your vote.
While the candidates and their campaigns work on the front lines to get votes; other groups with their own agendas are working behind the scenes to get their favorites elected.
It's the so-called dark money. Dark money comes from organizations that don't have to disclose who their donors are, unlike other contributions where the public gets to see who's backing their candidates.
This year's elections are said to be the "darkest" in U.S. history, with dark money pouring into races across the country at a rate three times that of the 2012 elections.
In Oklahoma's Senate race, dark money groups are flooding television stations with ads, many of them attack ads, spending more than the candidates themselves; and the candidates are quick to distance themselves, as they did in our debate.
Terry Hood: "Are you comfortable with the ads that they've been running? Do you stand by those?"
T.W. Shannon: "I'm not comfortable it because the challenge is I can't control it."
"We've had three weeks in a row we've put out statements that said we don't agree with any of this," Lankford said.
Even Senator Tom Coburn weighed in, attacking the outside groups' attacks ads. Now that attack is being used in another attack ad, by another dark money group.
So who are these secret donors?
Take the Foundation for Economic Prosperity, for example. It's spent hundreds of thousands of dollars supporting James Lankford.
While we can connect a few dots, we can't say for certain who is behind it.
On the other hand, Oklahomans for a Conservative Future, we know is linked a high-level executive at Manhattan Construction, but we don't know who else gives to the group; and it's address is a UPS Store in Oklahoma City.
It's spent 1.2 million dollars supporting T.W. Shannon. No one from the group has returned our calls and emails, requesting more information.
If you'd like to take a look at where the candidates stand on the issues and decide for yourself who you like, you can learn about all the candidates online.