Eighteen months into Jared Kushner’s White House tenure, his family’s real estate firm is deepening its financial relationships with institutions and individuals that have a lot riding on decisions made by the federal government.

In the latest example, an arm of Brookfield Asset Management is close to completing an investment of up to $700 million in the Kushner family’s tower at 666 Fifth Avenue in Manhattan. The deal will be a boon to the Kushners, who are struggling to recoup their investments in their flagship building.

At the same time, another Brookfield unit is awaiting the Trump administration’s approval of its acquisition of the nuclear-power company Westinghouse Electric. The deal is being reviewed by the Committee on Foreign Investment in the United States, made up of senior federal officials who consider the potential national security risks of transactions involving foreign companies. Brookfield’s headquarters are in Canada.

Mr. Kushner, who is President Trump’s son-in-law and senior adviser, has broad portfolios of both White House responsibilities and personal business interests — a combination that experts say has the potential to create real and perceived conflicts between his public and private roles.