Ah! We have an American challenging an American! But, mes amis, the American Code clearly states:

If either principal, on the ground, refuse to fight...it is the duty of his second to say to the other second: "I have come upon this ground with a coward, and have to tender you an apology for my ignorance of his character; you are at liberty to post him."

This is in the work by George Hooper, which is entitled "Down the River; or, Practical lessons under the Code Duello" (New York: E. J. Hale, 1874), p. 247.

Eh maintenant, you must reconcile, pluck, or be posted. It is your choice.