WASHINGTON — President Trump’s top economic advisers on Monday accused China of reneging on previous commitments to resolve a monthslong trade war and said Mr. Trump was prepared to prolong the standoff to force more significant concessions from Beijing.

Mr. Trump, angry that China is retreating from its commitments just as the sides appeared to be nearing a deal and confident the American economy can handle a continuation of the trade war, will increase tariffs on $200 billion worth of Chinese goods on Friday morning, his top advisers said.

“We’re moving backwards instead of forwards, and in the president’s view that’s not acceptable,” his top trade adviser, Robert Lighthizer, told reporters on Monday. “Over the last week or so, we have seen an erosion in commitments by China.”

Mr. Trump’s last-minute escalation highlights his administration’s difficult political position as it tries to fend off criticism that he has not been sufficiently tough on China. The president is facing pressure to show that the pain of his trade war will be worth it for the companies, farmers and consumers caught in the middle. Mr. Trump’s decision to potentially upend an agreement that many expected to be finalized this week in Washington appears to be a political calculation that staying tough on China will be a better proposition in the 2020 campaign.