The 2017 tax overhaul spurred a storm of lobbying activity starting this time last year—and it’s about to pick up again.

Now that Democrats have taken control of the House, they have the chance to fight back after watching Republicans pass tax reform. And tax lobbyists are preparing to defend the law against efforts to change provisions they like. Infrastructure investors, unions, the health care industry, and mutual funds, meanwhile, will almost certainly speak up about other tax and budget items on the Democratic Party agenda.

Chances are low that Democratic bills would be signed into law by a Republican president, but public hearings on the tax law and House floor votes on bills would help set the stage for 2020’s campaign messaging. Republicans need 60 votes in the Senate to bypass procedural hurdles, putting Democrats in a position to push for some tax priorities to be included in must-pass legislation.

Corporations “will want a seat at the table as opposed to being on the table,” said Thomas Reynolds, a senior policy adviser at Holland & Knight LLP who has recently lobbied on tax issues on behalf of Tesla Inc. Reynolds is a former Republican representative from New York and member of the tax-writing House Ways and Means Committee.

Most of the activity should take place in 2019, before both parties start “gearing up for the election” in 2020, Reynolds said.

The number of filings mentioning the 2017 tax law totaled nearly 3,600 in the fourth quarter of 2017. In the most recent quarter for which filings are available, which runs from July through September of this year, filings totaled about 1,500.

The speed of the lobbying ramp-up depends on whether Democrats initially dive into the bipartisan elements of their agenda, or take on one-sided pursuits: pushing for President Donald Trump’s tax returns or seeking to abolish Immigration and Customs Enforcement, the tax and lobbying professionals said.

Here are four things to watch.

1. Specialty Firms With Bipartisan Staff

Companies with the best chance of getting their prized provisions into final legislation will gravitate to lobbying firms with former staff from both sides of the Capitol and both sides of the aisle.

“People recognize the need to have a bipartisan, bicameral approach these days,” said Jennifer LaTourette, vice president of the lobbying firm Van Scoyoc Associates, who has worked for Republican and Democratic House members.

Companies and groups unaccustomed to tax lobbying also tend to turn to specialized firms, said Dan Auble, a senior researcher at the Center for Responsive Politics, who focuses on lobbying.

Capitol Tax Partners was the top tax reform-focused firm in the last quarter of 2017 and in the first three quarters of 2018, according to data from Bloomberg Government. In the fourth quarter of 2017, it advocated for 78 clients—including Amazon.com Inc., JPMorgan Chase & Co., and Raytheon Co.

The firm boasts seven former GOP staffers and three former Democratic staffers, according to its website. Of Capitol Tax Partners’ 13 lobbyists listed on the site, seven worked for the Senate Finance Committee, six held staff positions on the Ways and Means Committee, three worked for the Joint Committee on Taxation, and two worked in the Treasury Department.

Former tax staffers from the tax-writing committees are particularly valuable. And, there may be more headed to K street soon: Reps. Carlos Curbelo (R-Fla.), Erik Paulsen (R-Minn.) and Peter Roskam (R-Ill.), among others, lost re-election bids on Nov. 6.

“There’s still a lot of fixes left to do in the new tax law and those folks that have tax background will continue to be in command, no doubt about it. They will continue to hold their value, despite the fact that they’re in the minority. And they will continue to demand higher salaries on K Street compared to other staffers,” said Ivan Adler, a principal at The McCormick Group, an executive consulting firm.

2. Corporate Tax Overhaul Defense

Lobbying shops are prepping for a likely in-depth review of the tax law. While Democrats are unlikely to repeal it, they will need to negotiate changes to the law and other tax bills with a Republican Senate and president.

“They’ll be trying to figure out what happened and how we feel about it under a microscope,” Reynolds said, adding that Democrats will likely invite corporations to testify.

The transparency associated with such a review “is absolutely warranted,” said Caroline Bruckner, managing director of American University’s Kogod Tax Policy Center and former chief counsel on the Senate Committee on Small Business and Entrepreneurship.

A slight increase to the 21 percent corporate tax rate is also possible, LaTourette said. A rate increase could be used to pay for something like an infrastructure package.

Fans of the 20 percent pass-through deduction will push to keep it in place in the face of Democrats who don’t think it is helping small businesses, said a former Senate aide who spoke on the condition of anonymity.

3. Industries With a Stake in the Agenda

Next year will likely bring lobbying from a new crop of industries, based on the Democrats’ agenda.

Health insurers could stand to benefit from Democratic efforts to buttress the Affordable Care Act and may want to get involved, said Andrew Silverman, a Bloomberg Intelligence tax policy analyst.

Companies like Etsy Inc. and Amazon.com Inc. will likely want to have their say in online sales tax legislation in the wake of the U.S. Supreme Court’s Wayfair decision, which widened the scope of sales tax for online retailers, he said.

The same can be said for unions, utilities, builders, and infrastructure investors if Democrats follow through on their apparent appetite for public works projects often financed with tax-exempt bonds, he said.

And retirement issues will likely be a top focus, as they are a priority for Ways and Means ranking member Richard E. Neal (D-Mass.), the likely new chairman.

House Republicans in late September passed their tax 2.0 package with a retirement bill that was supported by 10 Democrats. The Senate is considering its own bipartisan legislation.

Those measures could fit into an end-of-year tax package, said AARP Legislative Counsel David Certner.

“And if they’re not, many of those packages—or pieces of those packages—will carry over into next year,” Certner said.

4. Pivot to OMB, Treasury

As lobbying ramps up in Congress, lobbyists will continue their focus on the Internal Revenue Service and White House regulatory review office.

The involvement of the White House Office of Management and Budget’s Office of Information and Regulatory Affairs in the regulatory process—per an April memorandum of agreement—has long been considered another chance for stakeholders to make their voices heard. Lobbying firms have been increasingly listing OMB as a government entity consulted on the tax law.

“There are certain levels of lobbyists and engagement,” said Ari Storch, president of Cascade Strategies and a partner at the Madison Group LLC in Washington. Some groups take a high-level approach to lobbying, while others get more involved in the technical side of things.

“In the more technical space, you have to do follow-through” at the regulatory level, he said.

--With assistance from Megan Wilson