Verizon Wireless' big advertising push for the Droid, the Motorola-made smartphone, appears to be working.

Mark Sue, an analyst at RBC Capital Markets in New York, estimates that as many as 800,000 Droids have sold since their Nov. 6 debut, according to Bloomberg News.

That puts the Droid, which runs on Google's open-source Android operating system, on track to sell 1 million this quarter.

The sales have been helped by Verizon's advertising campaign and well-stocked store shelves, Sue said. Verizon is positioning the Droid to challenge a new version of the iPhone. Apple sold more than 1 million of the latest model in its first weekend in June.

"Verizon's big marketing push for the Droid is strengthening as we close in on the holidays," Sue wrote in a note to investors. "Motorola for its part has done a good job on the production side, and our survey of over 100 stores indicates strong demand, limited stock-outs and very few returns."