The following week, John Edwards won the South Carolina primary and finished a strong second in Oklahoma to Clark. Lieberman dropped out of the campaign the following day. Kerry dominated throughout February and his support quickly snowballed as he won caucuses and primaries, taking in a string of wins in Michigan, Washington, Maine, Tennessee, Washington, D.C., Nevada, Wisconsin, Utah, Hawaii, and Idaho. Clark and Dean dropped out during this time, leaving Edwards as the only real threat to Kerry. Kucinich and Sharpton continued to run despite poor results at the polls.
In the 2004 Democratic presidential primaries, John Kerry defeated several Democratic rivals, including Sen. John Edwards (D-North Carolina.), former Vermont Governor Howard Dean and retired Army General Wesley Clark. His victory in the Iowa caucuses is widely believed to be the tipping point where Kerry revived his sagging campaign in New Hampshire and the February 3, 2004, primary states like Arizona, South Carolina and New Mexico. Kerry then went on to win landslide victories in Nevada and Wisconsin. Kerry thus won the Democratic nomination to run for President of the United States against incumbent George W. Bush. On July 6, 2004, he announced his selection of John Edwards as his running mate. Democratic strategist Bob Shrum, who was Kerry's 2004 campaign adviser, wrote an article in Time magazine claiming that after the election, Kerry had said that he wished he'd never picked Edwards, and that the two have since stopped speaking to each other. In a subsequent appearance on ABC's This Week, Kerry refused to respond to Shrum's allegation, calling it a "ridiculous waste of time."
North Carolina's party loyalties have undergone a series of important shifts in the last few years: While the 2010 midterms saw Tar Heel voters elect a bicameral Republican majority legislature for the first time in over a century, North Carolina has also become a Southern swing state in presidential races. Since Southern Democrat Jimmy Carter's comfortable victory in the state in 1976, the state had consistently leaned Republican in presidential elections until Democrat Barack Obama narrowly won the state in 2008. In the 1990s, Democrat Bill Clinton came within a point of winning the state in 1992 and also only narrowly lost the state in 1996. In the early 2000s, Republican George W. Bush easily won the state by over 12 points, but by 2008, demographic shifts, population growth, and increased liberalization in heavily populated areas such as the Research Triangle, Charlotte, Greensboro, Winston-Salem, Fayetteville, and Asheville, propelled Barack Obama to victory in North Carolina, the first Democrat to win the state since 1976. In 2012, North Carolina was again considered a competitive swing state, with the Democrats even holding their 2012 Democratic National Convention in Charlotte. However, Republican Mitt Romney ultimately eked out a 2-point win in North Carolina, the only 2012 swing state that Obama lost, and one of only two states (along with Indiana) to flip from Obama in 2008 to the GOP in 2012.

Question: Since what year have voters leaned Republican, in the state where the candidate who won the 2004 South Carolina Democratic primary was a senator?
Answer: 1976