Stewart was the Republican nominee for the U.S. Senate in 2018 in the commonwealth of Virginia,[1] losing to Democratic incumbent Tim Kaine by more than a 15-point margin.

[3] According to The New York Times, Stewart "made his name attacking illegal immigrants and embracing emblems of the Confederacy.

"[3] He drew national media attention for spearheading Prince William County's 2007 crackdown on illegal immigrants.

He drew media attention for his admission that his campaign staff had edited his Wikipedia page to add positive spin, his use of the term "cuckservative" in a Reddit "Ask Me Anything", and his staunch support for Confederate symbols and monuments.

[21][22][20] Stewart said in 2012 that his crackdown on illegal immigration had "cut violent crime in half", a claim PolitiFact rated "mostly false".

[29] In December 2015, Republican U.S. presidential candidate Donald Trump announced that he had chosen Stewart to chair his campaign in Virginia.

[5] Stewart has been an outspoken proponent of Trump in national media, and continued to support him even as other Republican officials disavowed him after various controversies, including the Access Hollywood scandal.

[36] Days later, the RNC and the Trump campaign announced that they were withdrawing from Virginia, again drawing the ire of Stewart, who criticized the decision as a betrayal of the grassroots and "totally premature.

[40] In a Reddit AMA, Stewart called his GOP primary opponent Ed Gillespie a "cuckservative", agreed with a participant who asked if Bill Clinton was a rapist, and wrote "CONFIRMED!"

[41] Virginia GOP chairman John Whitbeck rebuked the remarks, calling some of Stewart's language "racist", and noted that the term "cuckservative" is "used by white nationalists".

[41] Stewart also said that he and his campaign had been editing his Wikipedia page since at least May 2014 to remove unflattering information and add positive spin, through at least two registered accounts.

[46] During the campaign, Stewart distinguished himself among Virginia politicians by not condemning the white supremacists who marched in the Unite the Right rally in Charlottesville in 2017.

[47] Stewart said that the counterprotesters at the rally were to blame for "half the violence" and he condemned fellow Republicans who expressed disapproval of the white supremacist march.

[53][54] On July 15, 2017, Stewart announced his intention to seek the Republican nomination for the U.S. Senate seat held by Democrat Tim Kaine.

[56] In December 2017, it was reported that the Republican Party of Virginia leadership was "maneuvering with help from the national GOP" to block Stewart's nomination.

[61] In a tweet on December 8, 2017, Stewart revived the "birther" conspiracy theory by suggesting that former president Barack Obama's birth certificate and Roy Moore accuser Beverly Nelson's yearbook were forgeries.

[64] Stewart stirred controversy in June 2018 when it was reported that he had praised and paid far-right commentator Paul Nehlen.

[75] During a news conference in Falls Church, Stewart attempted to court Asian American voters by vowing to introduce legislation prohibiting institutions of higher learning from considering a student's race.

[76] In early October 2018, Stewart held a rally in Fairfax, Virginia, in support of U.S. Immigration and Customs Enforcement.

He expressed his support for the organization's officers and said he would work to "ensure not one penny of taxpayer money goes to welfare for those who entered our country illegally.

[79][80] In May 2019, Stewart shifted the focus of Keeping America Great to helping down-ballot Republicans after criticism from Trump campaign officials who preferred that donors direct their support in the presidential election to another super PAC.

[81][82][83] In November 2020, Stewart was appointed as the principal deputy assistant secretary for export administration at the U.S. Department of Commerce.

[84] According to Reuters, his appointment was intended to help the Trump administration advance "hardline policies on China" in its final months.