The former chief of staff of the Health and Human Services Department (HHS) during the Trump administration is running to succeed the late Republican Rep. Ron Wright of Texas.

Brian Harrison, a Texas native who served as deputy chief of staff and then chief of staff at HHS and who helped coordinate Operation Warp Speed ‒ the plan to develop a COVID-19 vaccine ‒ announced his candidacy on Monday.

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"Recruited by the Trump Administration to Deliver the AMERICA FIRST Agenda," the candidate touted on his new campaign website. And in an interview with the Fort Worth Star Telegram, Harrison said, "I want to keep the Trump movement alive."

Brian Harrison, the former chief of staff of the Health and Human Services (HHS) department during the Trump Administration, announces his bid for the vacant U.S. House seat in Texas' 6th Congressional District, on March 1. 2021. Harrison highlights a photo of himself with then-President Trump on his campaign website.

Wright, who died last month after testing positive for COVID-19, had just started his second term representing Texas' 6th Congressional District, which includes the southesat suburbs of Fort Worth and stretches into rural Ellis and Navarro counties.

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Susan Wright, the congressman’s widow and a well-known GOP activist, announced her candidacy last week. State Rep. Jake Ellzey, who narrowly lost to Wright in the 2018 primary in the race for the open seat, and who’s a veteran of the Iraq and Afghanistan wars, has also launched a campaign.

And Katrina Pierson, who served as a top adviser on President Trump’s 2016 and 2020 campaigns, is gearing up to launch a campaign, two sources with knowledge of her planning confirmed to Fox News on Monday.

The district, which was once considered safe for Republicans, has become more competitive in recent years. Wright won reelection in November by 9 points over his Democratic challenger. But Trump carried the district by just 3 points over now-President Biden.

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Candidates seeking to enter the race have until Wednesday to formally file the paperwork. Texas Gov. Greg Abbott last week formally declared Wright’s seat vacant, setting up a May 1 primary.