As the only Republican senator up for re-election in a state won by Hillary Clinton last fall, Dean Heller had a tough task ahead of him next year.

And that was even before he started enduring attacks from within his own party.

In 2011, Heller, then a third-term congressman, was appointed to the Senate seat by Gov. Brian Sandoval after GOP Sen. John Ensign’s retirement amid an ethics investigation. 

The following year, he won a full term under reasonably adverse conditions, considering President Barack Obama won the Silver State 52 percent to 46 percent over Mitt Romney. Heller defeated Democratic Rep. Shelley Berkley, 46 percent to 45 percent.

Not only did Heller fail to get a majority of the vote, but his opponent (Berkley) was under investigation by the House Ethics Committee. This cycle, the senator may not be as fortunate.

The most recent election results in Nevada are not encouraging for Republicans. Last cycle, GOP Rep. Joe Heck was regarded as a top-tier candidate but he lost to former state Attorney General Catherine Cortez Masto, 47 percent to 45 percent, in the race for former Senate Democratic leader Harry Reid’s seat. Clinton carried the state’s six electoral votes with a 48 percent to 46 percent victory over Donald Trump.

Some Republicans believe Heck fell short because he publicly backed away from Trump after the release of the Access Hollywood tape, angering enough Trump supporters to prevent the congressman from winning.

According to the exit polls, Heck won GOP voters, 86 percent to 8 percent. In comparison, Heller won Republicans, 90 percent to 5 percent, in his narrow 2012 victory. While both look like resounding victories, in close races, every percentage point matters. Winning Republicans by 85 points or by 78 points can be the difference between a statewide victory or a loss in a state as competitive as Nevada.

Heller is in danger of losing some votes from Trump supporters after opposing the draft Senate health care legislation crafted in response to the House bill. America First Policies, a pro-Trump outside group, went as far to air (and then pull) an attack ad against Heller for not going far enough to “repeal and replace Obamacare.”

It was a brazen move for the White House-aligned group to single out the Republicans’ most vulnerable senator for their attacks. 

Heller has enough to worry about, outside of problems within his own party. He faces a credible, if unproven, Democratic challenger in 3rd District Rep. Jacky Rosen. She was first elected last year to Heck’s open seat, which Trump narrowly carried. But she did it against perennial candidate Danny Tarkanian, who might have been the only Republican capable of losing that race. 

As a Republican senator with a potentially depressed base against a credible Democrat in a Democratic-leaning state, Heller is in for a rough ride this cycle. We’re changing the Inside Elections rating for the Nevada Senate race from Leans Republican to Toss-Up.