Is Sen. Mark Pryor really ahead in the U.S. Senate race?

That’s the finding of a new Talk Business-Hendrix College Poll, which says that Pryor leads his opponent, U.S. Rep. Tom Cotton, 45.5 percent to 42.5 percent.

The race hasn’t moved much in that poll since October 2013, when Pryor led, 42-41 percent. To win, the campaigns and their allies will be focusing their efforts in two areas. One is motivating the base to turn out to vote, and the other is going after the other 12 percent – the 8 percent who are undecided, the 2 percent who say they will vote for Libertarian Nathan LaFrance, and the 2 percent who say they will vote for Green Party candidate Mark Swaney.

In other words, expect a lot of political commercials in the next seven months. Control of the U.S. Senate may depend largely on the outcome of this race.

I need to disclose this somewhere: I’m a freelance journalist, and one of my clients is Talk Business. Back to the column.

This is just one poll. Despite its findings, Pryor still faces considerable headwinds, which is why if I had to bet money on who’s going to win, I’d pick Cotton. Momentum, history, and the year the election is occurring are not on Pryor’s side.

Let’s start with momentum – specifically, the Republican Party’s in Arkansas. Prior to 2008, much of the South – but not Arkansas – had switched from the Democrats to the Republicans. Since the election of President Obama, Arkansas has undergone a historic shift toward the GOP. When Obama was elected, the state’s congressional delegation was 5-1 Democrat. Now, it’s 5-1 Republican. Now-Sen. John Boozman defeated then-Sen. Blanche Lincoln by 21 points in 2010. The state Legislature has undergone a similar shift from Democratic domination to Republican leadership. In the 24 state Senate elections where the two parties have squared off since Obama was elected, the Republicans have won 19.

History also favors Cotton. Off-year elections often are unkind to members of the president’s party. Voters who oppose a sitting president are more motivated to vote than those who support him. In the 2006 elections during the second term of President George W. Bush’s administration, the Democratic caucus in the U.S. Senate gained six seats from 45 to 51 – the same number that Republicans need this year to take the Senate. In 1994 (after the Clintons also had tried to pass a health care plan), Republicans gained nine Senate seats.

Finally, there’s the year of the election. Under President Obama, two electorates have developed – a younger, more diverse one that votes only in presidential election years and leans Democratic, and an older, more conservative one that also votes in the other elections and gives Republicans an advantage. If Pryor would have faced re-election in 2016, he would be dealing with more favorable demographics. At the very least, President Obama would be less of an issue on his way out of the White House.

Of course, that would have meant Pryor would have had to run in 2010, when Lincoln lost by 21 points after Obamacare had passed. In 2008, Pryor didn’t even have a Republican opponent.

The issue that hangs over all of this, of course, is Obamacare. Pryor, as you must know if you are reading this kind of column, voted for it. To his credit, he hasn’t pretended that he didn’t, though I don’t see how he could. Obamacare will remain deeply unpopular in Arkansas through November, even if they do eventually get that website fixed.

Meanwhile, Pryor’s other disadvantages remain – momentum, which can be altered, and history and the year of the election, which can’t.