PROVIDENCE, R.I. (WPRI) – Democratic U.S. Sen. Sheldon Whitehouse plans to start airing TV ads for his re-election campaign right after Labor Day, according to orders placed with local broadcasters.

An Eyewitness News analysis of FCC filings shows Whitehouse has so far booked about $612,000 in commercial time on WPRI 12, WJAR-TV and The CW 28 starting Sept. 4 and ending Nov. 6, the day of the election. The total is likely to rise as more orders come in for those and other stations.

A Whitehouse spokesman declined to comment on the TV buys, which were placed last week. His campaign has already been paying to air digital video ads on Facebook, Twitter and Instagram since mid-June.

Whitehouse is facing Republican Robert Flanders, a former R.I. Supreme Court justice, in his bid for a third term. The incumbent has an enormous financial advantage: Whitehouse had $3.43 million on hand as of June 30, while Flanders had $384,000.

Flanders’ campaign did not respond to a question about when it plans to buy TV time.

Whitehouse is waiting longer to go on the air than the other Democratic incumbent at the top of the ticket in Rhode Island this year, Gov. Gina Raimondo, whose campaign began airing commercials in early June and expects to stay on the air through the election.

Ted Nesi (tnesi@wpri.com) covers politics and the economy for WPRI.com. He is a weekly panelist on Newsmakers and hosts Executive Suite. Follow him on Twitter and Facebook