Analyzing all the roll-call votes during the second session of the 112th U.S. Congress, the National Journal has put together a list of the most conservative members of the U.S. Senate. If you were to guess who earned the number one spot, you probably wouldn’t have said Sen. James Risch of Idaho — but don’t worry, you’re not alone.

“All of these guys rank on National Journal’s most conservative list, but none of them hold the top spot. That honor goes to James Risch of Idaho, a senator so obscure that he might as well be dubbed the Ann Veal of the Senate,” the National Journal reports.

The 15 Most Conservative Senators    And You May Have Never Heard of No. 1

Idaho U.S. Senator James Risch speaks during the GOP convention Friday, June 22, 2012 at the College of Southern Idaho campus in Twin Falls, Idaho. Credit: AP

A former Idaho governor, Sen. Risch was elected to the U.S. Senate in 2009 at the age of 65 and has not received much national attention during his tenure. However, when it comes to voting on conservative principles, he is a “true stalwart,” according to the National Journal.

Coming in second place is Sen. John Cornyn (R-Texas), followed by now retired Sen. Jim DeMint of South Carolina. In third place is Sen. Pat Toomey (R-Pa.) and in fourth Sen. Ron Johnson (R-Wisc.). Tea Party favorite Sen. Rand Paul (R-Ky.) rounds out the top five.

Full results will be published on Thursday, but here’s an incomplete list o the top 15 most conservative members of the Senate (Graphic by Peter Bell; Text by Ben Terris):

The 15 Most Conservative Senators    And You May Have Never Heard of No. 1

(National Journal)

The National Journal explains how the rankings are calculated:

For the past three decades, National Journal has rated members of Congress based on selected roll-call votes from the previous year to see how they compared with each other on an ideological scale. Unlike interest groups that rate lawmakers, National Journal does not attempt to say how members should have voted. Our goal is to describe how they voted in comparison with one another.

The ratings system was devised in 1981 under the direction of Bill Schneider, a political analyst and commentator, and a contributing editor to National Journal.

For the 2012 ratings, National Journal examined all of the roll-call votes in the second session of the 112th Congress—659 in the House and 251 in the Senate—and identified the ones that show ideological distinctions between members. Many votes did not make the cut—those that involve noncontroversial issues or that fall along regional lines, for instance. In the end, 116 votes in each chamber were selected and were categorized as economic, foreign, or social.

Do you agree with the list? Is there anyone you think should’ve made the top 15 but didn’t? Weigh in below.