The recent spate of activity from regulators is undoubtedly in part because of the higher level of deal-making. But supporters of the administration’s efforts also point to what they say are further attempts to consolidate industries that are already concentrated in the hands of a few companies.

“It’s not that the government has suddenly decided to become more aggressive,” said Diana Moss, the president of the American Antitrust Institute, a nonprofit that favors tougher antitrust enforcement. “We’re coming out of a phase where a lot of mergers were let through.”

Administration officials denied that they were now increasing the pressure.

In a conference call about the lawsuit against Halliburton and Baker Hughes, the head of the Justice Department’s antitrust division, William Baer, said that he was not trying to be more aggressive in trying to block mergers. Instead, he said, companies have been striking more deals — and betting that they will not have to make large changes to get those transactions approved.

“We are not changing how we look at or analyze mergers,” he said. “There are some deals that are so antitrust-risky that they never ought to make it out of the executive suite or the corporate boardroom.”

Obama-era regulators have blocked a number of blockbuster mergers, including AT&T’s $39 billion effort to buy T-Mobile USA and Comcast’s $45 billion bid for Time Warner Cable.

The Federal Trade Commission blocked an attempt by Sysco and US Foods to merge, which would have united two of the nation’s biggest food service providers.

Not all of the Obama administration’s antitrust efforts have succeeded. Despite initially suing to block the merger of American Airlines and US Airways, the Justice Department eventually withdrew its lawsuit and allowed the two to combine, creating the country’s biggest airline.