Every four years, while the rest of the nation heads to the polls, Washington’s coterie of lobby firms works overtime to tend to a mad rush of demands from corporate clients who all want to know the same thing: How do we best lobby a new president? A new Congress?

That season is now upon us. The fall and winter that bookend a presidential election are the busiest months for K Street’s hired guns. Late October is particularly harried, as they scramble to draw up contingency plans mapping out all potential outcomes of the election — presidential, House and Senate — and how companies should adjust their lobbying strategies accordingly. The most likely scenario at the moment looks to be a Democratic White House, a Republican-led House and an apparent Democratic majority in the Senate.

“The period from November to March around a presidential transition is probably the busiest time for lobby and public affairs firms,” said GOP lobbyist Stewart Verdery, who runs the lobby firm Monument Policy Group. “Trying to figure out how to engage a new administration, who the appointments are, changes with [congressional committee] chairmen. That’s a huge amount of work for clients. At least 60 percent of business development work is done in the next couple months.”

The momentum is reflected in the latest quarterly revenue figures reported by lobby firms Thursday. Many firms reported year-over-year revenue gains compared with 2015. Verdery’s firm picked up three new clients in the past six weeks and has earned $4.4 million in revenue so far in 2016 — up 7 percent compared with this time last year.

No matter who wins the White House, Congress is poised to tackle a handful of issues critical to the business community, like immigration, tax reform and infrastructure spending, said lobbyists of both parties.

“There’s going to be lots of business opportunities to focus on,” said Republican lobbyist Marc Lampkin, who heads the lobbying group at Brownstein Hyatt Farber Schreck. “You’re very likely to get, in the first six months, an overhaul of the tax code. You’re going to have some examination of both legal and illegal immigration. For the business community, legal immigration for a number of years has been a top priority. There’s going to be lots of businesses that are going to want to have an impact in Washington.”

Companies should also be paying attention to leadership changes in key congressional committees — particularly if Sen. Claire McCaskill (D-Mo.) takes over the Senate Permanent Subcommittee on Investigations, said Democratic lobbyist Zach Williams, a partner at Forbes-Tate. The firm earned $7.1 million so far in lobbying revenue this year — up 8 percent compared with last year.

The subcommittee, which is currently chaired by Sen. Rob Portman (R-Ohio) with McCaskill as ranking member, recently opened an inquiry into the drugmaker Mylan over the high price of the allergy auto-injector EpiPen.

“With McCaskill with the gavel, you’re looking at a much more aggressive investigatory arm,” Williams said. “There’s going to be a lot more companies brought in, whether it’s drug companies or others.”