The driver, Corinne Koenig, immediately phoned McMaster, her attorney, and he was present at the scene as Nancy Thurmond was transported to the hospital.

During his tenure, McMaster created the federal drug task force Operation Jackpot to investigate South Carolina marijuana smugglers.

His actions were criticized as political, with journalist Lee Bandy writing, "no one can recall any other U.S. attorney being so public-relations conscious" and noting that McMaster had held more press conferences and news releases than all his predecessors combined.

In 1986, after considering races for South Carolina lieutenant governor and attorney general, McMaster won the spirited Republican primary for the United States Senate against Henry Jordan, 27,696 votes (53.4%) to 24,164 (46.6%).

In 1991, Governor Carroll A. Campbell Jr. appointed McMaster to the state's Commission on Higher Education, and the South Carolina Senate confirmed him.

[43] After the U.S. Supreme Court overturned Roe v. Wade, McMaster said he "looks forward to the day we don't have abortions," and that he would sign any anti-abortion bill that came across his desk.

[51] McMaster is a strong supporter of the Second Amendment to the United States Constitution, the National Rifle Association of America, and legislation that gives citizens easy access to firearms.

[53] Student activist David Hogg, who survived the Parkland shooting, criticized McMaster, saying in a tweet that "future voters will not reelect you and outlive you too.

"[53] In 2021, McMaster signed a bill that allows South Carolina's citizens to open carry a firearm with a concealed weapons permit, which required holders to pass a training course and background check.

[55] In 2018, McMaster offered to send troops from the South Carolina National Guard to assist Texas in combating illegal immigration and drug trafficking.

[57] He called the troop mobilization an attempt to "stop the drug cartels, criminals, and terrorists from entering our country to peddle their poison".

[58] In 1993, as chair of the South Carolina Republican Party, McMaster criticized a bill cosponsored by Senator Fritz Hollings, a Democrat, that would prohibit workplace discrimination based on sexual orientation.

[59][60] In an October 2022 gubernatorial debate, McMaster said that if the U.S. Supreme Court overturned Obergefell v. Hodges, he would enforce South Carolina's preexisting legislation that banned same-sex marriage.

[61][62][63] In 2022, he signed a bill that requires student athletes from elementary school to college to play on the team that corresponds to the gender listed on their birth certificates.

On April 20, 2020, McMaster drew criticism for reopening beaches and retail stores five days after South Carolina experienced its highest number of new positive COVID-19 tests,[66] but he did include additional social distancing requirements in his executive order.

[68] By early June, McMaster reopened the majority of the state, though schools remained closed and businesses were required to follow social distancing procedures.

[71] He delivered the commencement address at West Florence High School's graduation ceremony and sang "Mull of Kintyre" while playing his guitar.

McMaster said, "it is up to the people to determine what kind of precautions need to be followed," indicating that he would not place any more restrictions on businesses and public facilities.

[76] Despite pleas from lawmakers and other state officials, McMaster declined to enact a statewide requirement to wear masks, saying that such an order would be unenforceable.

[77] Consequently, dozens of municipalities enacted their own mask requirement ordinances, including Columbia, Forest Acres, Greenville, Charleston, Lexington, and most large cities and towns.

[78] On July 10, as the state's COVID-19 cases exceeded 50,000 and nearly 900 deaths,[79] McMaster issued an executive order prohibiting businesses from selling alcohol after 11 p.m. in an effort to prevent the spread of the virus among younger people.

[80] On July 15, McMaster said in an address that South Carolina schools should give parents the option to send students to in-person classes in September 2020.

[91] Like President Trump, McMaster said that state and local governments were being too lenient on rioters and looters and was critical of Charleston's initial response.

[93] In 2017, McMaster, the University of South Carolina, BlueCross BlueShield, Columbia Mayor Steve Benjamin, and a number of prominent state legislators were connected to Richard Quinn and Associates, a firm he employed for political consulting.

[98] State lawmakers delayed the vote on McMaster's two nominees for two weeks, citing the ongoing corruption probe that had pulled in three Republican legislators.

[103] McMaster was in office when it was announced that SCANA and Santee Cooper were abandoning the expansion of the Virgil C. Summer Nuclear Generating Station in 2017.

"[111][112] McMaster's attorneys argued that the decision to use emergency funds for private schools should be decided by the voters or the South Carolina General Assembly, not a court order.

[119][120] McMaster has been an advocate of preserving the Gullah culture, an African American ethnic group who predominantly live in South Carolina's Lowcountry region.

[123] McMaster has also called for the preservation of South Carolina's environmental landscapes from "over-development, mismanagement, flooding, erosion or from storm damage.

"[131] In 2016, McMaster's tax return showed that he received $7.7 million in rent on such houses and apartments between 2006 and 2015; he paid a little over $500,000 for upkeep, maintenance, and cleaning.