If the polls are to be believed, Indiana Republican Sen. Richard Lugar will likely join some very rare company on Tuesday, becoming just the seventh senator in 30 years to lose his party’s nomination for reelection.

And Lugar’s tenure in the Senate — 36 years — would make it one of the more notable upsets in Senate history.

View Photo Gallery: Few incumbent senators have lost bids for their parties’ nomination over the last 60 years, making Sen. Richard Lugar’s (R-Ind.) potential loss on Tuesday all the more newsworthy. We look at Lugar and nine senators whose losses surprised us the most.

But where would it rank in the list of all-time upsets? Below, we rank the biggest primary upsets of an incumbent senator since 1950, including a potential loss by Lugar.

(Side note: Overall, about three dozen senators who have lost primaries over that span, with the vast majority of them occurring in the 1950s, 60s, and 70s.)

Did we miss any? Oversell any? The comments section awaits.

10. Utah Republican Sen. Robert Bennett (2010): Sen. Orrin Hatch’s (R-Utah) success in his convention fight this year makes Bennett’s third place finish in 2010 all the more amazing. While Hatch nearly won 60 percent of the vote at the state GOP convention last month (and would have avoided a primary if he had done so), Bennett didn’t even make the final ballot at the convention, finishing third to first-time candidate and now-Sen. Mike Lee and an unheralded failed congressional candidate in Tim Bridgewater. It was less surprising because the nomination process in Utah is prone to anti-incumbent elections, and because Bennett was basically caught flat-footed.

9. Tennessee Democratic Sen. Kenneth McKellar (1952): McKellar lost a primary in his effort for an unprecedented seventh term in the Senate in 1952 at the age of 83. The man who beat him has a familiar name: Albert Gore Sr. (a.k.a. the former vice president’s dad). McKellar had drifted to the right during his time in office and his loss wasn’t a huge shock (the state’s incumbent governor lost a primary that year too) but it’s notable that McKellar served as long as Lugar has and still lost.

8. Arkansas Democratic Sen. William Fulbright (1974): Perhaps best-known today for lending his name to the Fulbright Scholars program, Fulbright is one of the longest-serving senators to lose a primary. After three decades, Fulbright was defeated by a more conservative Democrat, then-governor Dale Bumpers — and it wasn’t close. Bumpers won 65 percent to 35 percent. Fulbright was 69 years old at the time and was seen as too dovish on foreign policy and the Vietnam War for his state.

7. California Republican Sen. Thomas Kuchel (1968): Kuchel lost to a more conservative primary challenger, state schools Superintendent Max Rafferty, after refusing to endorse more conservative California Republicans like Richard Nixon. His loss was notable because he was a Senate leader, serving as Everett Dirksen’s whip, and because he had been in office for more than three straight decades, including 24 years in statewide office.

6. Virginia Democratic Sen. Willis Robertson (1966): Televangelist Pat Robertson’s father lost his 1966 primary to state senator William Spong after clashing with then-president Lyndon Johnson. Robertson had opposed Johnson’s landmark 1964 Civil Rights Act and other similar efforts, and his loss was seen as the end of the line for Sen. Harry Byrd Sr.’s Virginia Democratic machine.

5. Indiana Republican Sen. Richard Lugar (2012): If Lugar loses it would be notable for two major reasons. First, because he is tied as the longest-serving Republican in the Senate, at six terms, Second, because Lugar has never really been known as a moderate. In addition, state Treasurer Richard Mourdock is hardly seen as a world-beating candidate. He lost five — count ‘em, five! — previous campaigns, including three congressional races, a secretary of state primary, and a 2004 race for city council. Not to mention he struggled to raise money early in this campaign.

4. Connecticut Democratic Sen. Joe Lieberman (2006): Lieberman’s loss to cable television magnate Ned Lamont was surprising both because Lamont came out of relative obscurity, only having served as a local selectman and having lost a state Senate race, and because just six years prior, Lieberman had been his party’s vice presidential nominee. Lieberman, of course, had spurned his party on the big issue of the day – the Iraq war – and became much more moderate in his later years. He went on to run as an independent in the general election and defeated Lamont with lots of Republican support.

3. Alaska Republican Sen. Lisa Murkowski (2010): Murkowski’s loss was a mix of the situations faced by Lieberman and Lugar. Like Lugar, she wasn’t really all that moderate, but still faced an ideological primary. And, like Lieberman, she faced a virtual unknown in businessman Joe Miller. Also like Lieberman, though, Murkowski ran in the general election without a party banner (as a write-in candidate, no less), and defeated the by-then-highly unpopular Miller.

2. Alaska Democratic Sen. Ernest Gruening (1968): The longtime former governor of then-territorial Alaska became one of the state’s first two senators in 1959, but lost a primary in 1968 to Mike Gravel (yes, that Mike Gravel) despite Gravel having lost several previous races and having only lived in Alaska for slightly more than a decade. Gruening suffered from being one of two senators to vote against the Gulf of Tonkin resolution and from a perception that he was simply too old . (He was 81 when he lost.) The Gruening family got revenge in 1980, though, when Ernest’s grandson, Clark Gruening, unseated Gravel in a primary.

1. Illinois Democratic Sen. Alan Dixon (1992): Dixon had been in elective office for more than four decades – including two terms as senator – when an unheralded African-American candidate, Carol Moseley Braun, upended him in a primary. Dixon suffered from his vote to confirm Supreme Court Justice Clarence Thomas and also from another moderate white candidate splitting his base of support. Dixon took a remarkably low 35 percent of the vote, and Braun won with 38 percent, later becoming the first black woman elected to the Senate. Dixon was the first incumbent senator to lose a primary in more than a decade.