threatening a veto, the President can persuade legislators to alter the content of the bill to be. more acceptable to the President. Congress can override a veto by passing the act by a two-thirds vote in both the House and the. Senate.(Usually an act is passed with a simple majority.) This check prevents the President from. blocking an act when significant support for it exists.his is referred to as a “pocket veto.” Since. The Presidential Veto and Congressional Veto Override Process Center for Legislative Archives National Archives and Records Administration www.archives.gov/legislative Congress cannot vote while in adjournment a pocket veto cannot be overridden.