The White House has begun drafting a new executive order that could further cement President Trump’s ability to control billions of dollars in scientific grants funded by the National Institutes of Health. Discussed at a highly contentious meeting at the White House on Friday, the directive aims to create a new external committee with the power to veto awards in the nation’s vast biomedical research portfolio that do not conform to Mr. Trump’s political agenda, according to people with knowledge of the effort.

The meeting was attended by Russell T. Vought, director of the Office of Management and Budget, and Dr. Jay Bhattacharya, the NIH director, whose relationship has grown so contentious that Mr. Vought had refused to meet with Dr. Bhattacharya. During the session, Mr. Vought accused the NIH director of funding projects that were in conflict with administration priorities, such as supporting research related to diversity and equity.

If the order moves forward, it would mark the latest attempt by the Trump administration to usurp the scientific autonomy of the NIH, a $48 billion agency that distributes a majority of its budget to labs across the country for research into areas such as heart disease, cancer and infectious diseases. Traditionally, the NIH selects projects based on expert review of their scientific merit. But Mr. Trump has sought through a series of recent directives in his second term to bring that process under political review, arguing in part that the government has been funding “woke” liberal priorities.

NIH officials insist all grant monies will be spent as planned, rejecting claims of funding cuts.