Republican presidential candidate, Sen. Ted Cruz, R-Texas, listens to a question during a campaign event, Thursday, Jan. 7, 2016, in Webster City, Iowa. (Jae C. Hong/AP)

Everything was going exactly according to plan for Ted Cruz and his presidential campaign. Until, suddenly, the question of whether he could actually serve as president — an issue that’s percolated around Cruz for years but had remained on the back burner during the campaign — boiled over.

Cruz was born in Canada. Calgary, to be specific. His mother was and remains an American citizen. That makes Cruz a citizen. But does it also mean he fits the definition of a “natural born citizen,” as the Constitution requires America’s presidents to be?

That is the question that Donald Trump — of course — raised this past week, first in an interview with The Washington Post and then in roughly 2 million follow-up interviews.

“Republicans are going to have to ask themselves the question: Do we want a candidate who could be tied up in court for two years? ” Trump said. “That’d be a big problem.” Later in the week Trump tweeted this advice to Cruz: “Go to court now & seek Declaratory Judgment.” Thanks, Donald!

Cruz initially tried to laugh the whole thing off, tweeting a video of Fonzie from “Happy Days” jumping the shark — Internet-speak for when something has passed its sell-by date, culturally speaking. Then he put out a more serious statement insisting that “people will continue to make political noise about it, but as a legal matter, it’s quite straightforward.”

That didn’t stop Sen. John McCain, long at daggers drawn with the senator from Texas, from twisting the knife during a radio interview. “I am not a constitutional scholar on that, but I think it’s worth looking into,” he said of Cruz’s eligibility.

Fighting back against insinuations that he might present a problem for Republicans if he is the nominee was not the way Cruz wanted to spend a week this close to the Iowa caucuses.

Ted Cruz, for being birthered by the master, you had the worst week in Washington. Congrats, or something.

Each week, Chris Cillizza awards the worst week in Washington to an inhabitant of Planet Beltway who stands out for all the wrong reasons. You can check out previous winners or e-mail Cillizza with candidates. You can also read more from Outlook and follow our updates on Facebook and Twitter.