The phrase "erstwhile opponent" means a person who was once an opponent or rival but is no longer in that position.
Sentences with «erstwhile opponent»
Klein, interestingly enough, ran on no fewer than four ballot lines in 2012, gaining access to the GOP line thanks to some peace making with erstwhile opponent Bronx County Chairman Jay Savino, who is now facing federal corruption charges for an alleged scheme to put fellow IDC Sen. Malcolm Smith on the Republican mayoral ballot through bribery. (nystateofpolitics.com)
Given that Canute gave his sycophants an object lesson in nature's indifference to lordly words it's bizarre of Monckton to denigrate erstwhile opponents as «bed - wetters, hand - wringers, and wolf - criers who populate the Church of Canutism... mesmerized by my status as a member (albeit non-sitting and non-voting) of the House of Lords» (wattsupwiththat.com)
His erstwhile opponent, Cassy Herkelman of Cedar Falls, advanced by default at Des Moines» Wells Fargo Arena. (religion.blogs.cnn.com)