The probability that we may fall in the struggle ought not deter us from the support of a cause we believe to be just; it shall not deter me.

Abraham Lincoln (1809-1865) American lawyer, politician, US President (1861-65)

Speech (1839-12-26), “The Sub-Treasury,” Illinois House of Representatives, Springfield
    (Source)

On defeating Martin Van Buren, the incumbent Democratic President, in the next election. Van Buren was in fact defeated in 1840 by Whig candidate William Henry Harrison.