EXPLAINER: Why the AP called S. Carolina for Lindsey Graham

South Carolina Republican Senator Lindsey Graham will return to the Senate for a fourth term.

That transformation, and his fiery 2018 defence of Mr Brett Kavanaugh after the Supreme Court nominee was accused of sexual assault, turned Mr Graham into a top target of Democrats' ire. National Republicans are also breathing a huge sigh of relief, as a Harrison win would have marked a remarkable encroachment of Democrats into traditionally Republican turf.

Lindsey Graham goes into Tuesday night with plenty of anxiety. As chairman of the Senate Judiciary Committee, Graham was tasked with shepherding the confirmation hearings, which began just three weeks before Election Day, as well as fending for his own seat. Harrison raised nearly $50 million in the third quarter and was tied with Graham in polls in October, but in recent days Graham pulled ahead in polling.

If Harrison had won, SC would have been the first state in US history to be simultaneously represented by two Black senators.

Harrison, a former Democratic Party official and a rising star in its ranks, made a bet that he could harness grassroots, anti-Graham energy to make himself a household name and galvanize turnout among the state's Black voters. Graham had sought to paint Harrison as too liberal for SC. In 2014, Graham beat his most recent Democratic challenger by almost 16 points.

While Harrison was well funded, Graham frequently called for campaign donations from viewers during appearances on Fox News.

"Tonight only slowed us down", Harrison said.

Mr Graham's loyalty to the president solidified following the death of Senator John McCain of Arizona, a longtime Mr Graham friend and Mr Trump antagonist.