PRINCETON, NJ — Although Barack Obama leads John McCain by almost 30 percentage points among 18- to 29-year-old registered voters, these younger voters are still less likely than older voters to report being registered to vote, paying attention to the election, or planning to vote this year.

Obama is clearly the favored candidate among young voters, while Obama and McCain are much more competitive among the older age groups.

Obama leads McCain by 62% to 34% among registered voters 18 to 29 years of age, based on Gallup Poll Daily tracking interviewing conducted Oct. 1-20. That’s a much larger margin than in any other age group. Among those aged 30 to 49, Obama maintains a 6-point margin. His lead is similar among voters between the ages of 50 and 64 (7 points). The two candidates are essentially tied among senior citizens. (Over this same period, Obama is leading McCain among all registered voters by 9 points, 51% to 42%.)

This strength of support for a Democratic presidential nominee among the youth is not a new phenomenon. In Gallup’s final poll before the 2004 election, the Democratic nominee John Kerry received 59% of the support of 18- to 29-year-old registered voters, while the Republican George W. Bush received 36% support. That compared to the overall sample of registered voters in which Kerry was leading Bush by 2 points, 48% to 46%. (Bush led Kerry among likely voters by 49% to 47%.)

Despite the skew among 18- to 29-year-old voters toward Obama, it’s important to note that their vote is not monolithically for the Democratic nominee. A general increase in voting among younger voters will bring one McCain voter to the polls for every two Obama voters. Thus, a general increased turnout among the under-30 voting group will increase Obama’s overall percentage of the vote, but most likely not as dramatically as would, for example, increased turnout among black voters, of whom 9 out of 10 prefer Obama.

There is evidence of an increase in new-voter registration and potentially higher participation among young voters given Obama’s appeal. But to what extent can Gallup’s large daily tracking samples provide insight into whether younger voters will in fact vote at high rates? Based on Oct. 14-20 tracking data, which include interviews with more than 6,500 registered voters, 18- to 29-year-olds still lag well behind older voters on key predictors of turnout.

At the most basic level, younger voters are significantly less likely than those who are older to report that they are registered to vote.

This is not a surprising finding. Young people are more mobile, less likely to have a permanent residence, and in general less plugged in to the political system. This year, there has been discussion about efforts to register young people (on college campuses, for example), but these data suggest that those in the under-30 group have a way to go before they are registered at the same rates as those who are older, particularly those aged 50 and above.

The data also show that younger voters, despite the sense that they are deeply involved in the political process this year, are less likely than those who are older to say they have given quite a lot of thought to the election.

Perhaps most importantly, younger voters are much less likely to self-report that they are likely to vote. One of Gallup’s series of likely voter questions asks respondents to place themselves on a 1 to 10 scale, where 10 means they will definitely vote and 1 means they definitely will not vote. The results show that those under 30 are significantly less likely to put themselves in the 9 or 10 position (definitely or almost definitely likely to vote) than is the case among their elders.

Gallup has found similar patterns by age in past elections, and the current data suggest younger voters still have a way to go to match the levels of registration, interest, and intention to vote of older Americans. That is not to rule out the possibility that young voters’ propensity to vote could increase in the final two weeks of the campaign, or that massive Democratic “get out the vote” efforts on Election Day could motivate many latent Obama supporters to officially register that preference in the voting booth.

Likely Voter Models

Gallup has used these measures — in addition to measures of past voting behavior — to identify likely voters in past elections, and these have proven successful in estimating the overall popular vote for president.

Because younger voters are less likely to answer these turnout-indicator questions in a way that would have Gallup identify them as likely voters this year, their share of the likely voting electorate as of mid-October appears as if it will be similar to what it has been in past elections.

Note that the proportion of 18- to 29-year-olds in the likely voter sample is similar even based on Gallup’s “expanded” likely voter model, which takes into account only a respondent’s current voting intention, and thus would give infrequent or new voters the same chance of being defined as a likely voter as those who vote regularly.

The expanded likely voter model’s estimate of the share of 18- to 29-year-olds in the electorate is only slightly higher than the estimate of Gallup’s “traditional” likely voter model. The traditional model is based on respondents’ current voting intentions and their past voting behavior, and although it does include adjustments for those who were too young to vote in the last presidential election, it would to some degree underestimate infrequent voters or new voters who could have voted in past elections but did not.

Turnout Estimates

Obama maintains a significant lead among 18- to 29-year-olds using both likely voter models — 60% to 37% using the expanded model, but a more narrow 54% to 42% using the traditional model, according to Oct. 14-20 tracking data. Among all likely voters over this period, Obama averaged a 51% to 44% lead in the expanded model and 49% to 46% in the traditional model. (Obama’s lead has increased slightly in recent days in both models.)

But what would happen if younger voters do make up a greater share of the electorate this year than what the Gallup likely voter models currently suggest — as, for example, would happen if there is a surge of younger voters responding to massive “get out the vote” efforts?

The accompanying table compares the Obama-McCain results among all likely voters 1) as estimated by Gallup; 2) assuming 18- to 29-year-olds will make up 18% of the electorate; and 3) assuming a surge of young voter turnout that increases their share of the electorate to a record 21% (with the three other age groups’ shares dropping by a point each).

These simulations suggest that Obama’s share of the vote would increase only if young voter turnout is much higher than it has been in the past, and at that, he gains only 1 percentage point. That is the case in both the expanded and traditional likely voter models, even though the expanded model gives young Americans and infrequent voters the same chance of being counted as likely voters as it gives Americans with a reliable voting history. McCain’s share of the vote could decline by 2 points if turnout is higher among young voters, but only if the assumptions of the expanded model hold — that is, that new and infrequent voters with strong voting intentions are just as likely to vote as are seasoned voters with the same intentions.Bottom Line

Gallup Poll daily tracking suggests that 18- to 29-year-olds are not nearly as likely as older voters to be registered to vote, to say they are thinking about the election, or to express strong intentions to vote. Thus, as of mid-October, there is not convincing evidence in the Gallup data that young voters will in fact vote at higher rates than in past elections. But even if things change over the next two weeks and many more young adults do become motivated to vote, turnout alone would do little to change the candidates’ overall support, according to Gallup’s likely voter models.

Gallup will continue to monitor the responses of 18- to 29-year-olds to the likely voter questions between now and Election Day to see whether the current situation changes.

Survey Methods

Results are based on telephone interviews with 7,063 national adults, aged 18 and older, which were conducted Oct. 14-20 as part of Gallup Poll Daily tracking. For results based on the total sample of national adults, one can say with 95% confidence that the maximum margin of sampling error is ±1 percentage point.

For results based on the sample of 604 adults aged 18 to 29, the maximum margin of sampling error is ±4 percentage points.

For results based on the sample of 6,508 registered voters, the maximum margin of sampling error is ±1 percentage point.

For results based on the sample of 484 registered voters aged 18 to 29, the maximum margin of sampling error is ±5 percentage points.

Interviews are conducted with respondents on land-line telephones (for respondents with a land-line telephone) and cellular phones (for respondents who are cell-phone only).

In addition to sampling error, question wording and practical difficulties in conducting surveys