DENVER -- With only a week left before the start of early voting, more than 6,000 people who registered to vote aren't eligible to cast regular ballots yet because they failed to check a box on their registration forms. The number is expected to rise since county clerks are still working their way through last-minute registration forms that came in before last week's deadline.

At issue is the part of the voter registration form that requires voters to either enter a driver's license or state identification number, or at least the first four digits of their Social Security numbers if they don't have state IDs. The form also asks voters to check a box if they don't have a state ID.

Election watchdog groups say the box check, required by state law, is an overly strict interpretation of federal law that they haven't seen in other states. On Monday, they called on Secretary of State Mike Coffman to automatically register people who have provided a Social Security number but didn't check the box. They said Coffman also could take other steps, including letting people complete their forms at early voting locations. They estimate that about 10,000 voters in the state could be affected.

"With such a close election, this many votes will have an impact," said Jenny Flanagan, executive director of Colorado Common Cause, one of eight state and local groups that sent a letter to Coffman asking for changes.

Coffman's office stands behind the form, which spokesman Rich Coolidge said was changed by Colorado lawmakers in 2006 on the advice of the federal Elections Assistance Commission.

Coolidge said clerks are sending out letters to all voters with incomplete forms, including those with empty boxes, advising them that they need to complete their forms. He said voters will be able to fix their forms at early voting locations as long as it's at the clerk's office or a satellite location, such as a motor vehicle office, staffed by county clerk workers.

If they don't get word of the problem or can't fix it before going to the polls, these voters will still be able to cast provisional ballots, he said.

Provisional ballots aren't included in the unofficial count of votes released on election night but are counted in the following days once election officials can verify that they were cast by eligible voters. Coolidge said people with incomplete registrations are being listed in the state's new voter registration database and their eligibility can still be checked later.

Sarah Brannon of the Fair Elections Legal Network, a nonpartisan network of election lawyers based in Washington, said the provisional backup isn't a complete guarantee because the law isn't clear on whether election workers can use the Social Security database to check voter eligibility after an election.

She said voters who have already provided a Social Security number to verify identity shouldn't be kept from voting with a regular ballot because of a formality. Brannon said that registration forms of other states she's reviewed tell voters that if they don't have state IDs, they can provide their Social Security numbers. Those forms don't ask for an affirmation that those voters don't have state IDs.

In the letter to Coffman, Brannon's group, Common Cause and others including the ACLU and the Lawyers' Committee for Civil Rights Under Law, allege that Colorado's approach conflicts with the federal "motor voter" law as well as the Voting Rights Act, which says people can't be barred from voting because of an "error or omission" on registration forms.

As of Monday, Coolidge said 6,462 applications have been labeled as incomplete because of an unchecked box. A total of 22,161 forms have been labeled as incomplete for a range of reasons, including a birthdate or address that doesn't match with state records. So far, more than 300,000 voter registration forms have been processed this year.

Link: Check your voter registration status

Boulder Residents Given Time To Fix Error

Residents and college students who registered to vote in Boulder County, but did not correctly complete a Colorado voter registration form, will have extra time to clear up any issues with their registration, the Clerk and Recorder's Office said.

The Clerk and Recorder's Office will send letters to people who need to correct their registration information. They will have until Election Day to complete their registration, said Jessie Cornelius of the Clerk and Recorder's Office.

"Voters who are notified should complete their registration information with the form they are sent and return it to our office as soon as possible," said Boulder County Clerk and Recorder Hillary Hall. "We want to ensure registrants know they can still correct their information and participate in the general election on Nov. 4."

The University of Colorado student union sent out an e-mail asking students to double check their registration status, saying many did not check the box on the form.

"A lot of us think we're registered, and we're not," said Ida Ghebre, a CU student who said she registered to vote on campus. "I checked the link and I wasn't registered and I don't know why."

UCSU Tri-Executive Ryan Biehle said he kept hearing the same story from various students.

"We wanted to make sure students were aware this could be a problem," he said.

He believes the problem is because many students don't have a Colorado driver's license, so they gave their Social Security number instead, and forgot to check the required box.

Registrants who have a Colorado driver's license or Department of Revenue Identification Number are required by law to provide their ID number on their voter registration form.

Voters who do not have these forms of ID are required to check the box indicating, "I do not have a Colorado Driver’s License or Department of Revenue Identification Number."

Voters would then need to provide the last four digits of their Social Security number.

"I think this gets to the broader issue of complicated voter registration system that's out there. In this state, we need voter registration reform," Biehle said.