Voters in 10 states with competitive Senate races have been inundated with more than $106 million in campaign propaganda, an analysis of independent expenditure reports and campaign expenditure records from the Federal Election Commission shows.

The total represents a combination of ad spending by outside groups and candidates' combined, and is likely a considerable understatement as candidate campaign committees' third-quarter filings have yet to be made public by the FEC.

But the spending we know about so far underscores the stakes involved as the two parties battle for control of the Senate, where Democrats currently hold a six-vote edge. Of ...