After coming within an inch of Democratic presidential frontrunner Hillary Clinton in the Iowa caucuses on Monday, Sen. Bernie Sanders (I-Vt.) all but claimed victory, proclaiming that his robust showing had delivered a shock wave to the "political establishment."

But while Sanders didn't win outright on Monday, the progressive populist did usher in an historic milestone. By winning even a single delegate in Iowa, Sanders, a secular Jew of Polish ancestry, has now won more delegates than any non-Christian presidential candidate in history.

Sanders emerged from Monday's caucuses with 21 delegates to Clinton's 22, according to projections from the Associated Press.

No non-Christian has come as close to the presidency as Sanders has.

Never before: Sanders isn't the first non-Christian to seek a major party's presidential nomination. Sen. Arlen Specter of Pennsylvania briefly sought the Republican nod in the 1996 cycle, and Sen. Joe Lieberman of Connecticut ran on the Democratic side in 2004. Both men were Jewish.

But in a country where more than 70% of the population still identifies as Christian, according to the Pew Research Center, no non-Christian has come as close to the presidency as Sanders has.

Lieberman, the Democratic Party's vice presidential nominee in 2000, once looked likely to end the Christian monopoly on primary delegates. After entering the 2004 presidential contest, he moved to a lead in the national polls, and though that lead had evaporated by the time the first nominating contests rolled around, he hoped to make a splash in the January 2004 New Hampshire primary.

Joe Lieberman sought to become the first major-party Jewish presidential nominee in 2004, but came up well short. Erik S. Lesser/Getty Images

It didn't pan out that way: Lieberman finished fifth with just 9% of the vote, netting zero delegates. After failing to pick up any support in a series of later contests, Lieberman withdrew from the race.

Sen. Barry Goldwater of Arizona, the GOP's 1964 presidential nominee, did have a Jewish father, but like his mother was a lifelong Episcopalian.

Another first? Sanders, who recently said at a Christian Science Monitor breakfast that he's "not particularly religious" but is "proud to be Jewish," is poised to mark another milestone next week.

When New Hampshire votes on Feb. 9, Sanders stands an excellent chance of becoming the first Jew and first non-Christian to win a presidential primary. The RealClearPolitics polling average currently gives Sanders an 18-point lead over Clinton, and Monday night's near-draw is unlikely to substantially sap his momentum.