As he fights for his political life, Gov. Henry McMaster could be getting a big boost on Monday as the two-week sprint to South Carolina's primary runoff comes to an end. In the final full day of campaigning, President Donald Trump is making a trip to West Columbia to campaign for McMaster's bid for a first full term in office. The presidential visit comes just hours before voters decide if they want McMaster or businessman John Warren as their GOP nominee for governor. McMaster was the top vote-getter in a June 12 primary but failed to get the 50 percent needed to win the nomination outright. Warren came in second, with 28 percent. The White House has been throwing everything at its disposal into the race to save McMaster, who went out on a political limb for Trump at a crucial point in the 2016 Republican presidential primaries. McMaster, the lieutenant governor at the time who was seen as an establishment figure, initially backed fellow South Carolinian Lindsey Graham's short-lived candidacy. After it folded, McMaster has said he fielded calls from many other GOP White House hopefuls before settling on putting his support behind Trump. 'He's a man of action,' McMaster said at the time. 'He speaks in words that everybody understands. It's a delightful thing to see.' Just weeks after his election, Trump selected Haley __ seen as a rising GOP star __ as his ambassador to the United Nations. Her departure cleared the way for McMaster in early 2017 to ascend to the governorship he had sought since losing a bruising primary to none other than Haley seven years earlier. Now, he seeks a full term on his own merit. Trump, who previously appeared at a McMaster fundraiser last fall, issued several tweets over the past week praising the governor and noting his loyalty. Vice President Mike Pence visited the state for a rally on Saturday. When voters in South Carolina return to the polls Tuesday, they'll be deciding in part which is more meaningful: a Trump endorsement, or a candidate who embodies some of Trump's outsider credentials. While the president has endorsed McMaster, Warren has positioned himself as the candidate who is the choice who more embodies the president himself. Like Trump, he's made millions in business, able to nearly self-fund his entire campaign. And like Trump, he's never before been directly involved in politics, spending his time in the private sector. South Carolina went solidly for Trump in 2016 and remains solid Republican territory. The winner on Tuesday will face Democrat James Smith in the general election. ___ Sign up for 'Politics in Focus,' a weekly newsletter showcasing the AP's best political reporting from across the United States leading up to the 2018 midterm elections: http://apne.ws/3Gzcraw. ___ Reach Kinnard at http://twitter.com/MegKinnardAP. Read her work at https://apnews.com/search/meg%20kinnard.