WASHINGTON — The amount of lobbying activity being reported has declined in President Trump’s Washington, but observers say it’s not because he is making good on his promise to “drain the swamp’’ of special interests.

The slow pace of legislation, stiffer rules, and a gradual decline in the number of lobbyists have contributed to the decrease in the first half of 2017.

The number of registered lobbyists has dipped to a low point, and special interests, after an initial burst in activity earlier this year, have in the past few months reported less spending than in almost any similar period in the past 10 years.

There were 9,791 registered lobbyists at the end of June, the fewest since at least 2008, according to a Globe review of the last decade of lobbying data collected by the Center for Responsive Politics.

Overall spending by special-interest groups has not increased over previous years, despite early predictions that there would be a ramp up in activity to mark a new administration.

“It’s surprising,’’ said Dan Auble, a senior researcher at the Center for Responsive Politics. “Everyone expects when there’s a change in party and agenda — and claims of changing a lot of policies — that it’s a huge opportunity for companies and industries.’’

But lobbyists, as well as those who study their activity, caution that the drop-off is probably not because Trump is successfully eliminating special-interest influences on government.

In fact, one reason there are fewer lobbyists is that Trump has hired them.

Public Citizen, a left-leaning research group, identified at least 133 employees appointed by the Trump administration who have a history of lobbying, nearly half of whom were active in the past two years.

The lower figures are also likely to reflect that little work is getting done in Washington, with fewer interest groups and corporations seeing reasons to spend money on a lawmaking process that is mired in dysfunction.

“Fortune 500 companies and associations are keen enough to realize this is not a normal unified government. Nothing much is getting done,’’ said Tim LaPira, a political science professor at James Madison University who studies the lobbying industry.

“All of that does impact what you can expect out of K Street,’’ he added, referring to the Washington street that has traditionally been home to interest groups and lobbying firms. “Organizations just aren’t going to throw good money at bad government.’’

The mood among lobbyists has shifted since just after the November election, when many thought they were in for a windfall. Republicans controlled all levers of power and had a big agenda, filled with issues that moneyed interests care about — including health care, taxes, and infrastructure.

But few of those things have been tackled, or even much discussed. Republicans spent most of the past few months grappling with an intraparty fight over health care — and never came to a resolution.

“We’re optimistic,’’ said Paul Miller, a lobbyist who is president of the National Institute for Lobbying and Ethics. “But maybe not as optimistic as we were on Jan. 1.’’

Lobbyists say they are ready to lobby, but the slow start to Trump’s administration has given them little to lobby over. The health care bill was written largely behind closed doors, without the kinds of opportunities that lobbyists look for to influence policy makers.

“You still don’t have key players in key administration jobs,’’ Miller said. “It’s just an agenda without a clear path, and people are saying, ‘Where are we going and how do we get there for our clients?’ ’’

Rule changes also may explain the decline in lobbying. President Obama cracked down on hiring lobbyists and required administration employees to sign a pledge not to lobby their former agency for a period of time after they left the administration. Trump has done something similar, although critics say that both Obama and Trump created a loophole by granting waivers.

One side effect of cracking down on the revolving door between lobbying and working in an administration is that lobbyists now have an incentive to avoid registering in the first place.

Lobbyists are required to register if they spend more than 20 percent of their time lobbying on behalf of a single client. So lobbyists can avoid registering if they have multiple clients — or if they do advisory work that doesn’t involve directly lobbying Congress or government agencies.

Special interests have also spent more money on influencing public opinion through advertising and grass-roots campaigns, rather than on traditional lobbying to change the minds of members of Congress.

Between the first and second quarters of this year, there were 32 fewer lobbyists.

Most years, there is an increase as Congress gains steam. In 2009, after Obama took office and Democrats controlled the House and the Senate, there were nearly 150 more lobbyists between the first two quarters of the year.

Trump’s campaign promises to crack down on the industry may have driven more of the influence underground, outside watchdogs said.

“At the beginning, there may have been a reaction from ‘drain the swamp.’ If you hear that and you’re a lobbyist who doesn’t have to register, or you can easily adjust things so you don’t have to register, then you’re not an alligator in the swamp anymore,’’ said Larry Noble, the Campaign Legal Center’s general counsel.

“As it became apparent that he really wasn’t going to change the rules, the incentive to do that is less and less,’’ he added. “He’s given a lot of waivers. He doesn’t even talk about ‘drain the swamp’ anymore.’’

Nor has the kind of spending increase that many expected materialized. The first quarter of the year had a brisk $862 million in lobbying activity — among the highest in the past 10 years — but there was a big drop-off in the second quarter, which ended June 30. Spending was $807 million, less than in any other year in the past 10 years except 2013 and 2016.

A review of lobbying records also shows a shift in priorities. Lobbying on energy and natural resources is down 23 percent, compared with 2009, while for health care it’s up 6 percent and for business it’s up 9 percent. The education and railroad industries are spending significantly less, while Internet, business association, and gun-rights industries are way up.

And while lobbying figures may be down so far — with the focus on health care — some expect that will not last.

“Its hard for me to imagine with the threat of the overhaul of the tax bill that people aren’t going to be hiring lobbyists,’’ Noble said. “My guess is it’s going to pop up again.’’

Matt Viser can be reached at matt.viser@globe.com.