During this time, the candidates seek last-minute support, while the party uses the free coverage by the broadcast media to appeal to the voters. On the third day of the convention, candidates for the presidential nomination are presented. Traditionally, the nomination speech for a candidate was followed by a supposedly spontaneous demonstration on his behalf. But the national television audiences became bored with these outbursts, and both parties have placed strict limits on the procedure. For 1972, the Democrats limited nominations in most cases to candidates with support in at least three states.
Nominations fall into distinct patterns.
The most common is the renomination of an incumbent president. Because of his national prestige and his power within the party, it is extremely difficult to defeat an incumbent. A similar pattern is the nomination of an apparent party leader without a significant contest at the convention. Nearly two thirds of the presidential nominations in the 20th century fall into this pattern. Most frequently, nominees are chosen in a single ballot.