Alaska Senate candidate Dan Sullivan (R) is attacking Alaska Lt. Gov. Mead Treadwell (R) in direct-mail pieces, according to the Alaska Daily News, a possible sign of a tightening race ahead of the Aug. 19 primary.

This is the first time Sullivan has gone after Treadwell directly in the campaign. The mail pieces hit Treadwell for ties to a company that received stimulus money.

Treadwell has trailed badly in fundraising, but Sen. Mark BegichMark Peter BegichPerez creates advisory team for DNC transition The future of the Arctic 2016’s battle for the Senate: A shifting map MORE (D-Alaska) and his allies have spent millions of dollars attacking Sullivan with ads seemingly designed to hurt him both with independents and the GOP base. Sullivan even accused Begich of meddling in the primary in a recent ad.

Alaska Republicans privately say that the race has tightened, though they say Sullivan still has the upper hand in the primary against Treadwell and 2010 Senate nominee Joe Miller (R).