Photo: The Canadian Press

Abandoning his previous restraint, President Donald Trump challenged the credibility of the woman accusing his Supreme Court nominee of sexual assault on Friday, declaring that if the alleged attack was so terrible she would have reported it to law enforcement.

Trump's change in tone — and apparent shift in tactics — came as Christine Blasey Ford's lawyers negotiated with the Senate Judiciary Committee on the terms for her possible testimony next week in a dramatic showdown over her accusation that threatens Judge Brett Kavanaugh's confirmation.

Trump tweeted: "I have no doubt that, if the attack on Dr. Ford was as bad as she says, charges would have been immediately filed with local Law Enforcement Authorities by either her or her loving parents. I ask that she bring those filings forward so that we can learn date, time, and place!"

The president previously had avoided naming Ford or plainly casting doubt on her account. Ford alleges Kavanaugh sexually assaulted her more than 30 years ago when they were teenagers. Kavanaugh has denied the allegation.

The accusation has jarred the 53-year-old conservative jurist's prospects for winning confirmation, which until Ford's emergence last week had seemed all but certain. It has also bloomed into a broader clash over whether women alleging abuse are taken seriously by men and how both political parties address such claims with the advent of the #MeToo movement — a theme that could echo in this November's elections for control of Congress.

With his comment, Trump went against the advice of advisers who had counselled him to stay out of the fray. But it was in keeping with his past defence of friends and other men against the claims of women.

Ford has said she didn't tell anyone at the time about the incident, as is often the case with victims of sexual misconduct. She told The Washington Post that she told no one about the episode in detail until 2012, when she was in couples therapy with her husband.

Trump's tweet could weaken GOP support among women going into the midterm elections. It could also threaten Kavanaugh's support with several Republicans -- including Sens. Susan Collins of Maine, Lisa Murkowski of Alaska and Jeff Flake of Arizona -- who have not declared their stances on his nomination. If two Republicans vote against Kavanaugh, his nomination could fail.

In another tweet, Trump, who was in Las Vegas for various events, wrote: "Judge Brett Kavanaugh is a fine man, with an impeccable reputation, who is under assault by radical left wing politicians who don't want to know the answers, they just want to destroy and delay. Facts don't matter. I go through this with them every single day in D.C."