There are multiple definitions of Potomac Fever, but for conservatives it means a politician who has abandoned his beliefs in free markets and limited government in exchange for being liked by his colleagues, receiving praise from the New York Times and Washington Post, and believing that he really is as great as all of his staffers say he is. This is also known as “growing in office.”

If Senator Jeff Flake (R-Beltway) had left Washington about five years ago, the right would be mourning his departure. In 2012, his last year in the House of Representatives, he had a perfect score on the American Conservative Union Federal Legislative Rating. His lifetime rating at that point was an impressive 97.

His best year was probably 2006. During that legislative session, he introduced 19 amendments that eliminated some of the worst examples of pork-barrel spending which, naturally, made him about as popular as Hepatitis C among his colleagues. Here’s what I wrote about it back then:

The Club for Growth has compiled 19 anti-pork amendments brought to the floor of the House by Congressman Jeff Flake between late May and late June of this year. It included votes to remove all-important spending initiatives like $1 million for the Mystic Aquarium in New Haven, CT., $180,000 for hydroponic water tomato production in Ohio, and $1 million for the Juniata Locomotive Demonstration. My favorite was $229,000 for dairy education in Iowa. (Having lived in Iowa for nine years, I offer this hint for those who want to learn about dairies: Find a farm with a cow.) I suppose that last one counts as improvement since it’s not $50 million for an indoor rainforest. Here are the results: 111 GOP members — almost half — voted against all of the anti-pork amendments. That included Jerry Lewis, chairman of the Appropriations Committee, and fearless leaders Majority Leader John Boehner and Majority Whip Roy Blunt. Over three-quarters of the members voted for less than half of the amendments, while only 19 voted for all of them. Indeed, just under twenty percent of GOP members voted for 13 or more of the amendments. (For a list of those taxpayer heroes, go here.) No amendment received more than 92 votes in favor, meaning that no single anti-pork amendment received even half of the votes of the GOP. That, in a word, sucks.

Flake was a bright light in a very dark period for conservatives, at least when it came to federal spending. A few years later the Tea Party movement would take up the pork-busting banner, and Congress would vote to end earmarks. Flake had prevailed.

Unfortunately, Flake then won a seat in the Senate. His first year in the upper chamber, 2013, was a portent of things to come. His ACU score fell to 72. His best year was 2014 when he scored 92; every other year was lower than 80.

His biggest sin was joining the “Gang of Eight” to promote “comprehensive immigration reform.” Anyone with half a brain always knew that was Washington-speak for “promise strong border security and amnesty but only deliver on the amnesty.” On one of the biggest issues of the last decade, Flake got it wrong. Very wrong.

So what happened? Perhaps Flake started believing all of the people in DC who frequently told him how silly free markets and limited government are. Or perhaps he just wanted to be liked by his Senate colleagues. We may never know for sure.

What’s certain is that his retirement from the Senate is the best thing he’s done in quite some time.

Crossposted at Bombthrowers.