PRINCETON, NJ -- Republicans maintain a substantial advantage over Democrats among likely voters in Gallup's generic ballot for Congress -- in both lower- and higher-turnout scenarios -- fueled in part by the GOP's strong showing among independents.
Gallup's latest election update shows that if all registered voters were to turn out, 44% of voters would favor the Democratic candidate in their district and 47% would favor the Republican candidate. The race has been close since the beginning of September, suggesting there has been little structural change in Americans' broad voting intentions in recent weeks.
Among voters Gallup estimates to be most likely to vote at this point under either a higher- or lower-turnout scenario, Republicans maintain substantial double-digit advantages. In Gallup's higher-turnout scenario, Republicans lead 53% to 41%. In Gallup's lower-turnout scenario, Republicans lead 56% to 39%. These likely voter estimates are based on respondents' answers to seven turnout questions, with the results used to assign a "likelihood to vote" score to each registered voter and, in turn, to create hypothetical models of the electorate based on various turnout scenarios.
In addition to turnout, independents' voting intentions are a critical determinant of the midterm election outcome -- particularly relevant, given that more than 90% of Democrats and 90% of Republicans say they will vote for their party's candidate in the elections. At this point, independents tilt strongly toward the Republican candidate in their district, helping shift the race in the GOP's direction.
Independents in general this year are more likely to lean toward identifying with the Republican Party than they are to lean toward the Democratic Party. Republican-leaning independents are also more likely to be classified as likely voters than are Democratic-leaning independents. Both of these factors work to the GOP's advantage among likely voters.
The Republican advantage among all registered-voter independents is 10 percentage points, 46% vs. 36%, underscoring the Republican tilt among independents even if all registered voters were to turn out. But among the two groups of likely voters, the Republican margin among independents expands to 21 to 25 points.
Republicans continue to benefit in the race for control of Congress not only from their higher representation among likely voters, but also from significantly higher identification with the GOP among independent voters.
Democrats have two general ways to close the gap with the GOP in the remaining weeks before the Nov. 2 election. First, Democrats could seek to shift the voting intentions of the electorate -- and more specifically, independents -- in a more Democratic direction. Second, they could work to increase enthusiasm and turnout among Democratic voters. President Barack Obama is out on the campaign trail -- and apparently will continue to be there between now and Election Day -- exhorting Democratically inclined voters to ratchet up their interest in voting on Nov. 2. The success or failure of these efforts will be a key determinant of the ultimate election outcome.
Explore more Gallup data relating to the upcoming congressional midterm elections, including Gallup's complete generic ballot trend since 1950, in the Election 2010 Key Indicators interactive.
Results for this Gallup poll are based on telephone interviews conducted Sept. 30-Oct. 3 and Oct. 7-10, 2010, with a random sample of 3,055 adults, aged 18 and older, living in the continental U.S., selected using random-digit dial sampling.
For results based on the total sample of national adults, one can say with 95% confidence that the maximum margin of sampling error is ±2 percentage points.
For results based on the sample of 2,747 registered voters, the maximum margin of sampling error is ±2 percentage points.
Results for likely voters are based on a sample of 1,953 survey respondents deemed most likely to vote in the November 2010 general election, according to a series of questions measuring current voting intentions and past voting behavior. For results based on the sample of likely voters, the maximum margin of sampling error is ±3 percentage points. Gallup provides two likely voter estimates using this sample. The lower turnout estimate assumes 40% national adult turnout and applies additional weights within the broad likely voter sample to match this turnout assumption. The higher turnout estimate gives all likely voters the same weight and represents a turnout level of 55% of national adults.
For results based on the sample of 891 independent registered voters, the maximum margin of sampling error is ±4 percentage points. For results based on the sample of 594 independent likely voters, the maximum margin of sampling error is ±5 percentage points.
Interviews are conducted with respondents on landline telephones (for respondents with a landline telephone) and cellular phones (for respondents who are cell phone-only). Each sample includes a minimum quota of 150 cell phone-only respondents and 850 landline respondents per 1,000 respondents, with additional minimum quotas among landline respondents for gender within region. Landline respondents are chosen at random within each household on the basis of which member had the most recent birthday.
Samples are weighted by gender, age, race, education, region, and phone lines. Demographic weighting targets are based on the March 2009 Current Population Survey figures for the aged 18 and older non-institutionalized population living in continental U.S. telephone households. All reported margins of sampling error include the computed design effects for weighting and sample design.
In addition to sampling error, question wording and practical difficulties in conducting surveys can introduce error or bias into the findings of public opinion polls.
For more details on Gallup's polling methodology, visit www.gallup.com.