LITTLE ROCK, Ark. — While a student at the University of Arkansas in 1985, Sen. Mark Pryor (D) wrote his college thesis on the state of Arkansas’ two-party system.

“The state’s Republicans have traditionally failed to produce politicians that Arkansas would elect,” he wrote. “The Democratic party, as a result, has thrived on a sort of perpetual motion.”

That perpetual motion came to an end Tuesday night. Voters chose Republican Tom Cotton over Pryor, and for the first time in 141 years, there will be no Democrats in Arkansas’ congressional delegation. Republicans also won the gubernatorial race and every other statewide race.

“Twelve years ago, the people of Arkansas gave me the greatest privilege of my life,” Pryor said Tuesday at his campaign’s election night party at the DoubleTree Hotel in Little Rock. He said he had called Cotton to “wish him the very best.” “I want you to know he will be in my prayers,” Pryor said.

Cotton, a 37-year-old Harvard and Harvard law grad and Army veteran who fought in Iraq and Afghanistan, tied Pryor to President Obama throughout the campaign, saying Pryor voted with Obama 93 percent of the time. He was disciplined about his message too, using everything from Ebola to President Bill Clinton’s visits to stump for Pryor to remind voters about Obama (“I’m not so worried about Bill Clinton’s support for Mark Pryor. I’m more worried for Mark Pryor’s support about Barack Obama,” he and his spokesman would say when asked whether they were concerned about the still-popular Clinton’s numerous campaign stops for Pryor in the campaign’s final weeks).

Pryor distanced himself from Obama, running ads highlighting differences he had with the president and presenting himself as a bipartisan more capable of working across the aisle than Cotton, who he said represented gridlock and supported the government shutdown.

But Obama is deeply unpopular in the state, with a 29 percent approval rating. Opposition to Obama energized Republicans, and even flipped some voters who’ve supported Pryor in the past.

“I know lots of Democrats who are voting for Republicans,” said Michelle Harris, 33, of North Little Rock before voting Tuesday. She said she wasn’t enthusiastic about Cotton, but wouldn’t vote for Pryor. The number one reason: His support of the Affordable Care Act.

The Republican sweep in Arkansas has been relatively swift. In 2010, Sen. John Boozman was the lone Republican member of Arkansas’ congressional delegation, but by 2013, Pryor was the lone Democrat, following Sen. Blanche Lincoln’s (D) loss.

“Arkansas has always been a very conservative state, but until 2010, we were probably the most Democratic state in the country,” Boozman said at a rally for Cotton in North Little Rock Monday. “That’s changed dramatically.”

But in 1985, when Pryor wrote his thesis, his father, David, was a member of the U.S. Senate, Bill Clinton was in the middle of his second run as governor, and, in Pryor’s estimation, there were “only four Republicans of election stature” in the whole state. He wrote that if the state were to change substantially and develop economically, Democrats could lose control.

“[I]f the state were to make it feasible for a large number of outsiders to settle down in Arkansas (i.e. retirement villages, high technology defense plants, etc.), these non-natives may not be inclined to vote Democratic,” he wrote.

His words were prophetic. The northwestern corner of the state has become a magnet for retirees, and as home to Wal-Mart and the vendors who work with Wal-Mart, a hub for jobs. The influx of out-of-staters there has been a factor in the state’s rightward shift, and Cotton frequently campaigned in the region.

“Arkansas’ leaving the South politically,” and behaving more like a Midwestern state than a Southern one in elections,” said James “Skip” Rutherford, dean of the University of Arkansas Clinton School of Public Service.

Arkansas' demographics — it's nearly 80 percent white, according to Census data — look more similar to nearby Midwestern states than neighboring Mississippi, which is nearly 60 percent white.

“Your election is going to be much more like Oklahoma and Kansas than it is like Georgia and North Carolina," Rutherford said.

It made it difficult for Pryor, who run unopposed in his last election, to overcome the odds despite running a “flawless” campaign, he said.

Pryor wrote in 1985 that Arkansans were “comfortable with the status quo” and their “unwillingness to try something new had a devastating effect” on Republicans in the state. It took nearly three decades, but finally, Arkansans seem ready for something new.

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