RICHARDSON (CBSDFW.COM) – Tuesday is the runoff election for Democratic challengers looking to face incumbents in two big Texas races. The winners will be on the ballot this November in the races for Governor and the 32nd Congressional District, facing Gov. Greg Abbott and Rep. Pete Sessions, respectively.

The runoff elections are being held because no candidate won at least 50 percent of the vote during the March primary.

The polls opened at 7:00 a.m. and close at 7:00 p.m. on Tuesday evening.

In the Governor’s race, former Dallas County sheriff Lupe Valdez is squaring off against Houston investor Andrew White for the Democratic nomination. Valdez previously received 43 percent of the primary election vote to White’s 27 percent. The winner on Tuesday will face a very popular Republican in Abbott.

White’s father was Texas Governor from 1983 to 1987.

In the race for the 32nd Congressional District, civil rights attorney Colin Allred received 40 percent of the primary vote in a crowded Democratic field. He is up against former Agriculture Department appointee Lillian Salerno for the nomination on Tuesday. The race is being closely watched by incumbent Sessions.

Democrats are hoping to flip a total of three Republican seats in the U.S. House. This would have once been unthinkable in a state as generally conservative as Texas. However, growing hostility toward President Donald Trump has members of the Democratic Party hopeful this year.

Meanwhile, Republican voters on Tuesday are also picking between State Rep. Lance Gooden and Bunni Pounds to replace the retiring Rep. Jeb Hensarling. Pounds is Hensarling’s former campaign manager. Plus, there is a runoff on both sides of the aisle to replace Rep. Joe Barton, who is retiring as well.

Early voting started last week, but turnout was low. Candidates are hoping that things will be different on Tuesday.