Is it ensure, insure, or assure?
late 14c., "prayers or pleas on behalf of another," from Old French suffrage (13c.), from Medieval Latin suffragium, from Latin suffragium "support, vote, right of voting," from suffragari "lend support, vote for someone," from sub "under" (see sub-) + fragor "crash, din, shouts (as of approval)," related to frangere "to break" (see fraction). The meaning "right to vote" is first found in the U.S. Constitution, 1787.
in representative government, the right to vote in electing public officials and adopting or rejecting proposed legislation.