PRINCETON, NJ -- One in three registered voters who are supporting the Democratic candidate in their congressional district say they are doing so because they "always vote Democratic." This explanation far exceeds any other when Democratic voters are asked in an open-ended fashion why they are supporting their chosen candidate.

Aside from party loyalty, at least 1 in 10 Democratic voters in the Sept. 30-Oct. 3 Gallup poll say they are voting Democratic because they agree with the candidate's agenda, because they are satisfied with the performance of their Democratic incumbent member of Congress, or because they dislike Republicans. Three percent say they are voting Democratic specifically to help support President Obama.

Republican voters' stated reasons for supporting the GOP congressional candidate are varied, with six different explanations offered by between 10% and 16% of respondents, the most common of which is that they favor the Republican candidate's agenda. Fifteen percent of Republicans mention party loyalty, a figure half as large as that among Democrats. Republican voters are also more likely than Democratic voters to say they are dissatisfied with their incumbent member's job performance (11% vs. 3%) and that they are voting for "change" (10% vs. 2%).

While most voters' responses revolve around general evaluations of the candidates or parties, 6% of Republican voters mention the specific issue of government spending as a reason they are casting their ballot for the Republican candidate in their district.

Despite the usual strong association between presidential approval and midterm election outcomes at the aggregate level, relatively few Republican voters seem to have President Obama top-of-mind when explaining their probable 2010 vote choice.

Bottom Line

Democrats' greater reliance on party loyalty to explain their vote this year may be another indication of a challenging political environment for their party. Recently, Gallup found many more Democratic voters saying their choice was more a vote for the Democratic candidate than against the Republican candidate, and Republican voters about equally likely to say their vote was for the Republican candidate as to say it was against the Democrat. Typically, the party that attracts a greater share of voters voting against the other party fares better in a midterm election.

Indeed, independent voters -- particularly those with a high likelihood of voting -- seem to be strongly inclined to vote Republican this year.

It is not clear whether the vote explanations that Republican and Democratic voters offer this year are typical for a midterm election year. Although Democrats are more likely to mention party loyalty as a reason for their vote, in one respect they are no more likely than Republicans to demonstrate party loyalty: nearly equal percentages of partisans say they are voting for their own party's candidate this year.