Democratic candidate for governor Steven Grossman says he may spend as much as $9 million to win his party's primary.

Grossman was required to submit the self-imposed limit as part of the state's public campaign finance law.

Grossman was one of three gubernatorial hopefuls who opted not to participate in the public financing system. Fellow Democratic candidates Martha Coakley, Joseph Avellone and Donald Berwick had agreed to participate.

Grossman's filing means all five Democratic candidates, including Juliette Kayyem who had set a self-imposed cap of $5 million, now have a top limit of $9 million for the primary.

On the Republican side Charlie Baker set a primary limit of $5 million. That will also now apply to fellow Republican gubernatorial hopeful Mark Fisher, who had sought public campaign funds.