Two others will be held in May in Knoxville and Memphis, after which, Smith said in a statement, "we then will raise whatever we need to raise to make sure Lamar is able to communicate his message and continue to represent Tennesseans."
The $4 million, however, will put Alexander in a comfortable position for reelection. He raised about twice that during his last race, and only spent about $6.5 million, winning with more than two-thirds of the vote.
Alexander could be vulnerable to a challenge from the right, as he is known as one of the Senate's more centrist Republicans, particularly considering the red lean of the state.
According to The Tennesseean, Alexander voted in support of President Obama's agenda more frequently than any other southern GOP senator in 2012.
But beginning his reelection campaign a year and a half out with more than $4 million cash on hand would help dissuade any Tea Party challengers from entering the race. He also named most of the Tennessee congressional delegation as his campaign co-chairmen, limiting recruitment options for Tea Party groups in the state.
His campaign also announced the support of a handful of Tennessee businesspeople and big donors, including FedEx CEO Fred Smith and Jim Haslam, businessman and father of Tennessee Gov. Bill Haslam.