PRINCETON, NJ -- Barack Obama's gain in support among registered voters from Monday to Wednesday of this week was in part the result of gains among conservative Democrats -- the group among whom the Democratic nominee had lost ground last week as he slipped to an overall tie with John McCain.

Obama and McCain were tied 45% to 45% among voters in interviewing conducted last week (Aug. 18-24). This represented a small decline for Obama, and analysis of the trend line of support for the two candidates among subgroups showed that it was due to a slippage among the relatively small group of Democrats with a conservative ideology. Now, with Obama holding a 6-point lead over McCain Monday through Wednesday of this week (Aug. 25-27), Obama has gained back that support and then some, moving from a 63% to a 77% level of support among conservative Democrats.

Obama has the support of 92% of liberal Democrats and 79% of moderate Democrats, basically unchanged from last week's percentages.

It is likely that conservative Democrats consist disproportionately of Hillary Clinton supporters, although this cannot be documented from the tracking data because no question about prior support of candidates is included. Analysis of Gallup Poll Daily tracking data from May, however, shows that conservative Democrats disproportionately supported Clinton over Obama for the Democratic nomination by a 48% to 43% margin -- more than her support from either moderate or, in particular, liberal Democrats. (Overall, Democrats in May tilted toward Obama by a 49% to 43% margin.)

This suggests that last week's drop in support for Obama may have resulted from defections by conservative Democrats whose loyalty to Hillary Clinton was brought to the forefront as the Democratic Convention approached, but whose angst Clinton assuaged with her strong support for Obama as the convention has unfolded.

At the same time, despite this hypothesis about the movement of Clinton supporters, and despite the high-profile campaign speeches women -- including Michelle Obama and Hillary Clinton -- gave on Monday and Tuesday nights, Obama's gains in the early days of this week did not come disproportionately among women. He gained 3 points among women, and 3 points among men.

Survey Methods

For the Gallup Poll Daily tracking survey, Gallup interviews no fewer than 1,000 U.S. adults nationwide each day, generally including approximately 880 registered voters. The results reported here are based on telephone interviews with 2,723 national adults, aged 18 and older, conducted Aug. 25-27, 2008. For results based on this sample, one can say with 95% confidence that the maximum margin of sampling error is ±2 percentage points. For results based on the subsample of 1,411 registered Democrats and Democratic leaners, the maximum margin of sampling error is ±3 percentage points.

Results for the week of Aug. 18-24 are based on interviews with 6,205 national adults, aged 18 and older. For results based on this sample, the maximum margin of sampling error is ±1 percentage point. For the subsample of 2,076 registered Democrats and Democratic leaners, the maximum margin of sampling error is ±2 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 can introduce error or bias into the findings of public opinion polls.

To provide feedback or suggestions about how to improve Gallup.com, please e-mail feedback@gallup.com.