DES MOINES — Republican voter registration has surged in Iowa with about two-thirds of the GOP’s gain coming at the expense of Democrats.

Overall, the number of registered voters in Iowa a month before the Nov. 2 general election has grown by just 161, according to the October voter registration report from the Iowa Secretary of State’s Office. With early voting under way, there are 2,106,831 Iowans registered to vote.

That represents 92 percent of Iowans eligible to vote, based on voting age population totals from the Election Assistance Commission and George Mason University’s Election Project.

However, the number of voters registered as Republicans has increased 36,070 since a year ago. Democratic registration is down by 23,786 and no party registrations have fallen by 12,371, the Secretary of State reported.

No party is still the leading choice for Iowa voters, with 759,072 registered. That’s down 12,371 from a year ago.

The numbers are “evidence of the momentum that exists for the Iowa Republican Party and our candidates,” GOP Chairman Matt Strawn said Friday. “It’s an indication Iowans are lining up behind the GOP.”

Although there are fewer Iowans registered as Democrats than a year ago, the party has a 54,224-voter lead on Republicans in the latest monthly summary, said Iowa Democratic Party spokesman Sam Roecker. There are 700,111 Iowans registered as Democrats compared with the 645,887 registered as Republicans.

That spread is greater than it was four years ago when Gov. Chet Culver was elected, Roecker said.

The numbers are consistent with the past few months and put the party and its candidates in “a great position going into the final weeks” of the 2010 campaign, Roecker said.

The secretary’s numbers show a decline in registered voters since October 2008 when there were 2,111,809 Iowans registered to vote. There were 724,535 Democrats and 620,779 Republicans on the registrations rolls then.

The decline in voters identifying themselves as Democrats follows a national trend, according to Rasmussen Reports, which has been tracking voter identification for nearly eight years. For the second month in a row, the number of Americans who identify themselves as Democrats has fallen to a record low.

In September, 34.6 percent of American adults identified themselves as Democrats. That’s down nearly half a percentage point from the previous month and a full percentage point from two months ago, Rasmussen said. It’s the smallest percentage of Democrats ever recorded in nearly eight years of monthly tracking.

At the same time, the number of Republicans nationally slipped from 33.8 percent in August to 33.1 percent last month.

Nationally, the number of adults not affiliated with either major party is now at 32.3 percent.

According to Rasmussen, Democrats have outnumbered Republicans every month for the past eight years. Their advantage was 5.6 percentage points in September 2008 and 4.8 percentage points in 2006.

Republicans came closest to closing the gap just ahead of the 2004 presidential election when Democrats’ advantage was just 0.6 percentage points.

Compared to a year ago, the number of Democrats in down 3 percentage points and the number of Republicans has grown a point.