The proportion of voters identifying with the Democratic Party has grown significantly since the 2004 election, and the shift has been particularly dramatic among younger voters. Fully 61% of voters ages 18 to 29 identify or lean Democratic and a comparable percentage supports Barack Obama. But Democratic gains in party affiliation among older voters since 2004 have been much more modest. Moreover, support for Obama among voters ages 50 and older is slightly lower than the share of this cohort that identifies with the Democratic Party.

In Pew surveys conducted since August of this year, 51% of all voters say they think of themselves as Democrats or lean toward the Democratic Party, up five points from 46% during the same period in 2004. Meanwhile, the number identifying with or leaning toward the Republican Party has fallen from 45% to 41%. In this cycle, the Democratic Party enjoys a 10-point advantage in party identification, compared with a one-point edge in the fall of 2004.

The greatest gains for the Democratic Party have come among younger voters. The percentage of voters ages 18 to 29 identifying with the Democratic Party has increased from 48% in the fall of 2004 to 61% currently. Democrats now outnumber Republicans by a margin of nearly two-to-one (61% to 32%) in this age group, up from only a seven-point advantage in 2004.

Voters ages 30 to 49, a group that includes the more conservative “Generation X, “also have shifted considerably since 2004. Nearly half (49%) of voters in this age group identify with or lean toward the Democratic Party, up from 43% in 2004. Democrats currently have a six-point advantage over Republicans among voters in this age group; at a comparable stage in the last campaign, Republicans had a six-point advantage. However, voters who are now in their early to mid-40s, a cohort that came of age politically in the Reagan years, remain one of the most Republican-oriented age cohorts; they are about evenly divided between Democrats and Republicans.

Baby Boomers, many of whom are now ages 50 to 64, have long leaned Democratic as a generation, and this remains the case today. Currently, just over half of voters in this age group identify with or lean toward the Democratic Party (51%) up slightly from 47% during the 2004 election. The Democratic advantage over the GOP among this age group has grown from two points in 2004 to 10 points now – about the same as the national total.

Only among voters age 65 and older has the percentage of voters identifying with the Democratic Party decreased slightly — from 49% in 2004 to 47% now. This slight decline reflects the passing of members of the New Deal Generation — who leaned overwhelmingly Democratic but who are mostly in their 90s now. In addition, voters who came of age politically in the Eisenhower administration, and are now in their late 60s, are closely divided in their party affiliation.

The relative stability of partisanship in this age group reflects the fact that these voters have been politically active for the longest period of time and may have the firmest partisan affiliations.

Party Identification and the Vote

Although Democrats have a 10-point party identification advantage over Republicans (51% vs. 41%) in the six surveys Pew has conducted since August, Barack Obama’s lead over John McCain aggregated across the same surveys has been slightly narrower (49% vs. 41%).

The difference is mostly due to older voters. Obama draws overwhelming support from both older and younger Democrats; however, his lead among Democratic voters age 50 and older (84% to 9%) is somewhat narrower than his lead among those younger than age 50 (90% to 5%). As a result, while Democrats have a seven-point lead in party identification among voters age 50 and older (49% to 42%), Obama runs nearly even with McCain among voters in this age group (45% vs. 44%).

In the fall of 2004, when Democratic and Republican Party identification (46% vs. 45%) was nearly even heading into the presidential election, so too was overall candidate support (45% Kerry and 46% Bush in polls conducted between August and Election Day). Support for Kerry tracked fairly evenly with Democratic Party identification for both older and younger voters. Among voters under age 50, 44% supported Kerry and 45% identified as Democrats. Similarly, 46% of those age 50 and older supported Kerry and 48% identified with the Democratic Party.

Shifts in Party Identification Among Whites

Overall, more whites continue to identify as Republicans than as Democrats (48% vs. 44%); this is narrower than the 52%-to-40% advantage the GOP held in 2004. Since then, Democratic Party identification has increased four points (from 40% to 44%) among white voters.

Notably, the balance of party identification among younger white voters has reversed, from an 11-point advantage for the GOP in 2004 to an 11-point advantage for the Democrats today. However, the 51%-to-41% Democratic advantage among white voters ages 18 to 29 is much smaller than the 29-point advantage Democrats hold among all voters under 30.

Among white voters ages 30 to 49, the Republican Party holds an eight-point advantage in affiliation, which is far smaller than their 19-point lead at this stage in 2004. However, this continues to be the most Republican-leaning age cohort among white voters.

The share of white voters ages 50 to 64 identifying with the Democratic Party has increased slightly from 43% in 2004 to 45% in 2008. Meanwhile, Republican identification has fallen from 51% to 47%, leaving the GOP with a slim two-point advantage, down from an eight-point advantage in 2004.

Party ID and Vote Preference among Whites

The gap between partisan leaning and support for Obama is particularly clear among older white voters. As is the case with younger voters overall, the share of younger white voters who affiliate with the Democratic Party and the share that supports Barack Obama is almost identical. However, among white voters ages 50 and older, substantially fewer support Obama than identify with or lean to the Democratic Party. There was no such gap in 2004, when the balance of party and the balance of support for John Kerry was virtually identical across all age groups.