By David Shepardson

ARLINGTON, Virginia (Reuters) -U.S. lawmakers are considering changes to address concerns about a bill that would give the Biden administration new powers to ban Chinese-owned TikTok, the chair of the Senate Intelligence Committee who has cosponsored the legislation said on Monday.

Democratic Senator Mark Warner told Reuters that aggressive lobbying by the ByteDance-owned short video app TikTok against the Restrict Act "slowed a bit of our momentum" after it was introduced in March.

Warner said lawmakers have "a proposal on a series of amendments to make it explicitly clear" and address criticisms, including that individual Americans could be impacted or that the bill represents a broad expansion of government power.

"We can take care of those concerns in a fair way," Warner said.

The legislation endorsed by the White House would grant the Commerce Department new authority to review, block, and address a range of transactions involving foreign information and communications technology that pose national security risks.

"I will grant TikTok this - they spent $100 million in lobbying and slowed a bit of our momentum," Warner said, adding that initially it seemed it would be almost "too easy" to get the bill approved.

TikTok did not immediately respond to a request for comment on Warner's assessment of its lobbying.

In March, Republican Senator Rand Paul blocked a bid to fast-track a separate bill to ban TikTok introduced by Senator Josh Hawley, who said the Restrict Act "doesn't ban TikTok. It gives the president a whole bunch of new authority."

The Biden administration in March demanded TikTok's Chinese owners divest their stakes or face a U.S. ban. Attempts in 2020 by then President Donald Trump to ban TikTok were blocked by U.S. courts.

Warner said there are a lot of conversations about the bill, adding it could be attached to an annual defense bill or could be part of a China-related bill that Senate Democratic Leader Chuck Schumer wants.

The need for legislation is clear, he said.

"There have been another three or four apps that have come out that are Chinese controlled so we need a fair rules-based process to deal with this rather than kind of a one-off basis," Warner said.

TikTok, which is used by more than 150 million Americans, says it has spent more than $1.5 billion on rigorous data security efforts and rejects spying allegations.

The company is fighting a ban by the state of Montana set to take effect on Jan. 1. A judge has scheduled an Oct. 12 hearing on TikTok's request.

(Reporting by David Shepardson; Editing by Leslie Adler and Sonali Paul)