An estimated 20,000 Rock Island County residents will have voted before Election Day, according to county officials, which based on historical turnout numbers could make up one third of the votes cast in the general election.

In Mercer County, 838 early, absentee and mail-in votes had been cast by early Friday out of approximately 12,800 registered voters, according to the Mercer County Clerk's office. Henry County Clerk Barb Link reported 2,429 early votes Friday out of roughly 36,000 registered voters.

By Friday morning in Rock Island County, 18,175 ballots had been cast through early or mail-in voting, and by Monday evening that number is likely to hit 20,000, said Rock Island County Chief Deputy Clerk John Brown.

There are around 92,000 registered voters in the county but with turnout for presidential elections usually at around 75 percent, Mr Brown expects roughly 69,000 votes will be cast, with votes cast before election day likely to make up close to 30 percent of that total.

In the 2008 presidential election, 14,500 early votes were cast in Rock Island County. But early voting rules at that time required voters to have "cause" to vote early, which meant they had to declare they were unable to vote on election day. New rules allow anyone to vote early.

Mr. Brown said early votes will be counted after polls close at 7 p.m. next Tuesday along with the votes cast on election day.

In Rock Island County, early voting stations have been running at Moline Public Library, the Rock Island County Office Building and on the voter trolley, which tours the county.

Mr. Brown said about 450 votes a day have been cast at the county building since early voting started, and 350 or so ballots have been cast daily at the library, with between 150 to 200 voters casting ballots on the trolley a day since Oct. 22.

The grace registration period, which allows residents who are not registered to vote to do so provided they vote straight after, ends Saturday. On Monday, only registered voters will be allowed to vote early.

Republicans and Democrats are both using early voting to flush out their base before election day.

Rock Island County Republican Party Chairwoman Susie Carpentier said this is the first election in which the party has focused its resources on getting people to vote early.

Republicans have been working from their call center in East Moline to identify people likely to vote GOP since the Spring.

Early voting allows the party to push supporters to vote early, after which they can be crossed off the list and party volunteers can move to the next target.

Democrats across the country ask supports to sign a pledge to vote early. The campaign technique then allows the party to follow up and ask the supporter if they have fulfilled their pledge.

Rock Island County Democratic Party Chairman Doug House said the party locally has been working hard to identify its supporters and then turn them out during the early voting period.Early voting, he said, also has forced campaigns to get their message out much earlier than in the past.