Republican strategist and Jeb Bush adviser Mike Murphy offers Bloomberg Businessweek readers an assessment of how 2016 presidential campaigns are likely to ramp up in 2015.

How will the field of presidential candidates take shape this year?
We used to call it the invisible primary. Even though we consider 2016 the election year, a lot of the political activity happens in 2015. What’s happened now, with the explosion in what I call the process press, the Politicos, etc.—not to mention cable news networks—is the invisible primary has become incredibly visible. But 2015 is the year in which you try to raise a lot of money, build a national finance committee, and start to actually engage primary voters.

What size bankroll do you need to be a legitimate candidate?
In the old days you used to say that you’ve got to have $25 million raised by Jan. 15 of election year. It was always kind of a phony yardstick. What I care about is cash in the bank on Jan. 1, 2016.

So what’s the range?
I think you’ve got to be in the double-digit millions. You’ve got a long, dry year where you can spend a lot of money talking to voters who aren’t engaged yet or who are happy to change their opinion from one candidate to another, and you can sink a huge cost into organizational stuff and have very little to show for it if you’re not careful. 2015 is a dangerous and difficult time for the dark-horse candidates, who can go broke trying to break through. Though it’s also a dangerous time for the front-runners, because they can stumble and be perceived to have a narrative of going from strong to weak.

Follow the link above to read Murphy’s analysis of several presidential contenders.