The polling change does not mean that voters in the 19 states will not be surveyed; they will still be polled for the national exit poll, but the estimates of political stance, race and age at the state-level for the excluded states won't be included in the survey. Those estimates have been in place since 1992.
A number of changes in how voters cast their ballots was also factor in the decision. The increasing number of people who vote early has added to the costs of the poll getting accurate samples, and the cost of conducting phone surveys for the poll has also increased because of the growing number of people who use cellphones.
For the 2012 election, exit pollsters are surveying voters in 15 states by phone. The sample size of those surveyed will increase by 32 percent, Merkle said.
The states states that won't be included in the exit poll are Alaska, Arkansas, Delaware, District of Columbia, Georgia, Hawaii, Idaho, Kentucky, Louisiana, Nebraska, North Dakota, Oklahoma, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, West Virginia and Wyoming.
—This story was updated at 1:03 p.m.