Sen. Dean Heller (R-Nev.) announced at a Las Vegas news conference last week that he will vote against the proposed GOP health-care bill. (Erik Verduzco/Las Vegas Review-Journal via AP)

When Sen. Dean Heller (R-Nev.) came out in opposition to the health-care legislation last week, it was a surprise that, in hindsight, shouldn't have been a surprise.

Heller is an extreme version of the five to six senators who just politically can't vote for the bill, mostly because they fear it will yank away health care for hundreds of thousands in their respective states.

His opposition more or less killed this version of the bill, which was written in secret by Senate Majority Leader Mitch McConnell (R-Ky.). And you should keep following what Heller says about it, because his support could almost single-handedly bring it back to life.

There are two main reasons there is just no way Heller could have voted for this bill as is. Consider:

1) Heller is the most vulnerable GOP senator up for reelection 2018:

  • He is the only Republican senator up for reelection in a state Hillary Clinton, not President Trump, won.
  • His elections have always been tight; he first won his Senate seat in 2012 by a margin of just 12,000 votes out of almost 900,000 cast.
  • new poll shows the Senate's version of the health-care bill is definitely not popular among the independents that Heller needs to win his 2018 race.

(So far he has one challenger: Freshman Rep. Jacky Rosen (D-Nev.).)

2) His state has tangibly benefited from Obamacare:

  • Nevada's GOP Gov. Brian Sandoval took Obama up on expanding Medicaid, which helped cut its uninsurance rate in half. (The Senate's bill would slash the federal government's funding for the health-care program for the poor by $722 billion over the next decade.)
  • Nevada is struggling with opioid addiction. Heller revealed Friday that his own mother became addicted to opioids after back surgery. (The Senate's bill has a fraction of the $45 billion that GOP senators want the federal government to give for addiction treatment services.)

Like every other Republican, Heller still maintains that Obamacare needs to be fixed. But there's nothing he can sell about a bill that the nonpartisan Congressional Budget Office estimates will cause 22 million more people to become uninsured and spike elder, low-income people's insurance premiums by 280 percent more over the next decade.

Given all that, it makes sense that Heller was the first moderate GOP senator to announce that he would vote “no.”

Here's how much he hates this legislation: The normally press-adverse senator held a news conference in Las Vegas on Friday, Nevada's Republican governor by his side, and knowing all of Washington was watching him, said: “I cannot support a piece of legislation that takes away insurance from tens of millions of Americans and hundreds of thousands of Nevadans.”

Heller held a telephone town hall Tuesday night that raised even more eyebrows. The normally declaration-adverse/controversy-adverse politician unloaded on the bill and Trump.

Nevada Independent journalist Jon Ralston was listening in:

We've spent all this time talking about one senator who opposes the legislation. Republican leaders have two “no” votes to divvy up and pass a version of this bill. They could theoretically give one to the symbolic leaders of the GOP's two separate “no” camps — Heller on the moderate side and Sen. Rand Paul (R-Ky.) on the conservative side.

But if Heller can't get on board, there's little reason to think the half-dozen moderate senators who also hate this bill will. Heller's “no” has given cover to some of them to do the same. Even a nasty ad campaign by a pro-Trump group linking Heller to House Minority Leader Nancy Pelosi (D-Calif.) hasn't deterred them.

Here's Sen. Susan Collins (R-Maine) talking to reporters outside the Capitol on Tuesday, a couple days after Heller's news conference: “I have so many fundamental problems with the bill that have been confirmed by the CBO report that it's difficult for me to see how any tinkering is going to satisfy my fundamental and deep concerns about the impact of the bill.”

“Tinkering will not do it,” declared Sen. Bill Cassidy (R-La.) in a Wednesday morning CNN interview. “If we scale back Medicaid, which is good, we need to make it so that somebody goes off Medicaid for private insurance.”

And Sen. Shelley Moore Capito (R-W.Va.) told CNN that she can't vote for a bill that will undercut the 184,000 people in her state who are now insured via Medicaid because of Obamacare: “I've said repeatedly, I'm not going to drop you off a cliff, and in my view, the Senate bill was too much of a cliff.”

None of the above Medicaid senators are up for reelection in 2018 (though Collins could run for governor in Maine that year). Heller is. And his politically perilous situation, combined with the fact that his state represents an amalgamation of problems the Senate's health-care bill doesn't address, makes him the bellwether for his camp of opposition.

If Heller can get to “yes,” it's likely that the rest of the moderate senators can, too. And that would go a long way in helping revive Senate Republicans' health-care bill from the dead.