(Stations: UPDATES with new information throughout) BILLINGS, Mont. (AP) Montana Republicans abandoned their challenge to almost 6,000 voter registrations today, after county election officials said they would reject thousands of the challenges as invalid.

Republicans had notified the counties last week that they were challenging the registrations of 5,977 voters whose addresses didn't match a U.S. Postal Service database. Party leaders said they were trying to guard against voter fraud.

The maneuver drew criticism from state and county election officials who had to investigate the claims. Nonpartisan voter rights groups said there was no proof of fraud in the state and said it was partisan-driven.

Challenged voters could've been forced to reregister or submit an affidavit proving their current address.

In a letter sent to election officials in seven counties today (Tuesday), Montana Republican Party executive director Jacob Eaton said he was withdrawing the challenges and would be issuing no more.

By AP writer Matthew Brown (Copyright 2008 by The Associated Press. All Rights Reserved.) APNP 10-07-08 2033CDT | save this article / add to your favorites list