If Hillary Clinton takes her candidacy all the way to the Democratic National Convention in Denver, she will point to two members of the party’s historic firmament to justify her case — Woodrow Wilson and Franklin Roosevelt.

Already beset by criticism and calls to drop out of the presidential race, Mrs. Clinton, by the time the convention comes around, will need an argument that the Democratic Party is strong enough to survive a contentious and drawn-out election.

Should Mrs. Clinton remain in the race through the convention, she or her allies may need to remind Americans about the conventions of 1912 and 1932. Delegates voted 46 consecutive times at the 1912 convention before settling on Wilson as the nominee, according to a history of presidential elections, “The Glorious Burden.”

Wilson, the former president of Princeton and eventual nominee, didn’t have the lead after the first of many ballots. Eventually, thanks to winning the support of an old Democratic lion, William Jennings Bryan, Wilson captured the nomination.

The nomination of Roosevelt in 1932 went overnight and required four separate ballots. In both cases, prominent and ultimately successful Democrats did not win their party’s nominations on the first ballot, a fact that could help Mrs. Clinton’s struggle to become the nominee at the convention.

A careful student of history will note that there are important differences between today’s convention and those of the past. Both Wilson’s and Roosevelt’s campaigns took place when party nominees needed to win a 2/3 majority, not the simple majority Mrs. Clinton needs today.

It’s too early for the Clintons to begin talking about Wilson or Roosevelt. First, she will need to win big in Pennsylvania. But as the primary contests wind down and the days leading to the convention approach, I predict Mrs. Clinton will reach into her back pocket and pull out these two important Democratic allies. They will be the best kind of friends for her, because unlike living former allies, such as Governor Richardson, who endorsed Mr. Obama, they can’t, as dead men, prevent the Clintons from speaking in their name.

Senator Clinton supporters say that the ugly conventions and multiple ballots did little to undermine the Democratic candidate in either 1912 or 1932. Wilson won 40 out of the 48 states in the general election. Roosevelt defeated Herbert Hoover, taking 42 states to the Republican’s six. If the nomination of candidates as strong as Wilson and Roosevelt took multiple ballots, without any negative effect in November or on history, the least Democrats should do is let Mrs. Clinton stay in the race.

Mr. Gitell (gitell.com) is a contributing editor of The New York Sun.