Republican Kathaleen Wall put an additional $210,000 of her own money into her campaign for Congress on Tuesday and has now spent a total of $4 million in her bid to replace retiring U.S. Rep. Pete Olson, R-Sugar Land.

Wall is battling in a 15-person Republican primary and is by far the biggest spender. The other Republican candidates in the race have combined to spend $2.2 million for the 22nd Congressional District seat. The district includes most of Fort Bend County, parts of northern Brazoria County and southeastern sections of Harris County.

Most of Wall’s spending has been on ads that have saturated local TV stations as she aligns herself with President Donald Trump. She’s tried to make the case during her campaign that she is the candidate who can best help Trump fight illegal immigration and build a border wall with Mexico.

Wall, a longtime GOP campaign donor herself, has a history of spending big on her campaign. In 2018, she spent $6.2 million in a GOP primary for the 2nd Congressional District in Houston but finished in third place.

Know the candidates: Houston Chronicle 2020 primary election voter guide; San Antonio Express-News 2020 primary election voter guide

The only other candidate in the Republican primary for the 22nd District with even $1 million to spend in the race has been Pierce Bush, the grandson of former President George H.W. Bush. Just since the start of 2020, Bush has raised over $425,000, including donations from former Houston Astros great Nolan Ryan, Gallery Furniture owner Jim “Mattress Mack” McIngvale and Houston Texans CEO Cal McNair.

“It has been humbling to see so many people step up and support this campaign,” Bush said.

In his campaign mailers, Bush has said he’s the candidate who can help Trump most in Congress. In those mailers, he stresses his support for building the border wall where it is needed and adding more Border Patrol agents.

Former Pearland City Councilman Greg Hill has raised just under $400,000 for his campaign, which includes $40,000 in loans to it. Fort Bend Sheriff Troy Nehls has raised $303,000 but is also getting help from a Super PAC called One Tough Sheriff that has reported raising just short of $100,000 to support Nehls.

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Wall isn’t the only big self-funder in the race. Republican and retired Marine Jon Camarillo has raised $117,000 for his campaign, but $100,000 of that is a loan from himself to it. Businessman Bangar Reddy has raised $113,000, including at least $25,000 in loans he’s made to his campaign. No other candidate in the GOP primary has more than $100,000 to spend on the race.

Wall this week also picked up big endorsements. U.S. Sen. Rand Paul, R-Ky., is supporting her campaign. Paul partly grew up in Brazoria County while his father Ron Paul was a congressman. Rand Paul graduated from Brazoswood High School and attended Baylor University.

Bush has his own share of big endorsements. Olson, former U.S. Rep. Ted Poe, R-Atascocita, actor Chuck Norris and former Astros pitcher Roger Clemens have backed Bush’s campaign.

For subscribers: Houston-area Congressional District 22 has nation’s biggest GOP primary field

Election day is March 3.

Democrats Sri Preston Kulkarni, former Pearland City Councilman Derrick Reed, attorney Nyanza Davis Moore and retired electrician Carmine Petrillo III are battling in the Democrat primary. Kulkarni, who won the Democratic nomination in 2018 but lost to Olson, leads the field in fundraising. He has raised $1.2 million. Reed has raised $156,000, and Moore has raised $150,000.