Rhodes Cook’s blog has this interesting calculation, showing that this year, Mitt Romney has won 38% of the votes cast in Republican presidential primaries, and 33% of the vote cast so far in Republican caucuses. Cook notes that there has never been a Republican presidential nominee who polled such a low share of the nationwide presidential primary vote for his party, during the era in which a majority of states have held presidential primaries. The first presidential election in which a majority of states held presidential primaries was 1976.

Cook notes, however, that several Democratic nominees polled almost that low a share of the Democratic presidential primary vote. The lowest percentages for Democratic nominees were Walter Mondale’s 38% in 1984, and Jimmy Carter’s 39% in 1976. Rhodes Cook is the author of America Votes, the nation’s most accurate and thorough reference books for election returns for federal office.