Story highlights 52% of voters say they're more likely to back a candidate who opposes Trump

Democratic advantage now mirrors their edge in January 2006

Liberal Democrats most enthusiastic about voting this year

Washington (CNN) As the midterm election year begins, a new CNN poll conducted by SSRS finds the Democratic advantage on a generic congressional ballot has tightened to a narrow 5 points among registered voters, but those voters who say they are most enthusiastic about turning out to vote this fall favor Democrats by a wide 15-point margin.

The new poll's 49% Democrat to 44% Republican margin among registered voters is almost identical to Democrats' standing in January of 2006, the last midterm election year in which they made significant gains in the House of Representatives.

But it represents a large shift from CNN polls conducted in the past three months, in which Democrats held double-digit advantages over the Republicans. Preferences among all adults have shifted less dramatically, but are also tighter than last fall, with Democrats currently 10 points ahead of Republicans among all Americans.

Enthusiasm about voting in this year's contests has grown as the calendar page has turned, with a spike among Republicans and Republican-leaning independents from 32% feeling extremely or very enthusiastic about casting a ballot in December to 43% saying the same now. Democrats still hold an advantage in enthusiasm, however, with 51% saying they are that enthusiastic about voting in this year's midterm elections.

Enthusiasm for this year's contests peaks among liberal Democrats, 62% of whom say they are deeply energized about voting. Among conservative Republicans, just 46% say the same.

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