A monthly business confidence index for Massachusetts employers posted a 51.1 reading in October, down from a 51.3 reading in September, but an analysis of the data used to calculate the index suggests that Bay State employers are deeply concerned about the so-called “fiscal cliff.”

The fiscal cliff is a term that describes the steep tax hikes and deep spending cuts that go into effect in January unless Congress reaches a compromise on reducing deficits.

The business confidence index is maintained by the Associated Industries of Massachusetts, or AIM, an organization that represents Bay State employers. Issued monthly since mid 1991, the index is calculated on a 100-point scale, with 50 as neutral. A reading above 50 is positive, and a reading below 50 is negative.

Advertisement - Continue Reading Below

Besides an overall index reading, AIM also examines several sub indices. One of those sub indices looks at national conditions, and that sub index dropped 5.6 in October to a reading of 39.4.

“That’s a recessionary number,” said Andre Mayer, AIM’s senior vice president of research.

What’s troubling Massachusetts employers is not so much the outcome of Tuesday’s presidential election, but the political deadlock in Washington, according to the AIM analysis.

In a statement, Raymond G. Torto, chair of AIM’s Board of Economic Advisors, commented on the latest index readings.

“The political polls have shown a closely divided national electorate, perhaps increasing concerns among our survey sample of deadlock in Congress just as Congressional action becomes most urgent,” Torto said.