WASHINGTON, D.C. (WNAX) – A Des Moines Register poll released over the weekend shows Democrat challenger Theresa Greenfield with a 46-43 percent lead over incumbent Republican Senator Joni Ernst. That could set the stage for a Democratic takeover of the Senate in November.

South Dakota Senator John Thune, the number two Republican in the Senate, says they know it will be competitive.

Thune says a lot can change by November.

Thune says the re-election campaign of President Trump will play into control of the Senate.

Democrats have to flip four of the Senate seats to take control.