Compared to the other two current polling frontrunners, Donald Trump and Senator Ted Cruz, Rubio is increasingly being viewed as the more mainstream candidate in the race. If so, he may have a very different track to succeed: He will have to clean up in an unusual place for Republicans—the Blue States.

In a general election, Rubio has practically zero chance of getting an electoral vote from the vast majority of the Northeast and West. Yet, in a primary campaign, states like California, New York and Illinois may provide the path to victory.

What may be surprising about this strategy is that he is far from the first candidate to try to use it. He wouldn’t even be the only one this year. During her early struggles, there had been discussion of a Hillary Clinton “Southern Firewall”—where she would fend off a Bernie Sanders or Joe Biden run by sweeping the Southern states that will undoubtedly vote Republican in November.

This strategy of looking to an electorate that the candidate had no hope of winning in the general election to ward off a strong primary challenge goes back to the very beginning of the presidential primary. Neither Clinton nor Rubio may want the association, but William Howard Taft used this exact plan to fend off Teddy Roosevelt in the 1912 presidential campaign.