WASHINGTON -- U.S. President Donald Trump denounced Democratic efforts to block Brett Kavanaugh's Supreme Court confirmation as a cynical "con job" on Tuesday and launched a dismissive attack on a second woman accusing the nominee of sexual misconduct in the 1980s, asserting she "has nothing."

Senate Majority Leader Mitch McConnell predicted that Kavanaugh would win approval, despite the new allegations and uncertainty about how pivotal Republicans would vote in a roll call now expected early next week. Like much of America, lawmakers awaited a momentous Senate Judiciary Committee hearing in which Kavanaugh and chief accuser Christine Blasey Ford are to testify Thursday, though not together.

Committee Chairman Chuck Grassley said Arizona prosecutor Rachel Mitchell will be brought in to handle questioning of Kavanaugh and Ford. Mitchell comes from the Maricopa County Attorney's Office in Phoenix, where she is the chief of the Special Victims Division, which covers sex crimes and family violence.

Hanging in the balance is Trump's chance to swing the high court more firmly to the right for a generation. Despite McConnell's forecast that Republicans will "win," Kavanaugh's fate remains uncertain in a chamber where Republicans have a scant 51-49 majority.

"I will be glued to the television," said Sen. Susan Collins, a moderate Republican from Maine, who has yet to declare her position on confirmation.

Hoping the hearing will yield no new surprises, the Senate Judiciary Committee scheduled its own vote on Kavanaugh for Friday, and Republican leaders laid plans that could keep the full Senate in session over the weekend and produce a final showdown roll call soon after -- close to the Oct. 1 start of the high court's new term.

Given that the Judiciary Committee's GOP members are all male, McConnell said the panel was hiring a "female assistant" to handle the questioning for Republicans "in a respectful and professional way." Grassley, R-Iowa, identified Mitchell in a press release late Wednesday, describing her as "a career prosecutor with decades of experience prosecuting sex crimes."

"My gut is they're trying to avoid a panel of all white guys asking tone-deaf questions," said Democratic Sen. Chris Coons of Delaware.

Each senator on the 21-member panel will be allowed five minutes to ask questions, said committee spokesman Taylor Foy. That's a tight rein for such a major hearing.

Meanwhile, the Republicans were still assessing what Kavanaugh's Monday interview on the Fox News Channel -- an unusual appearance for a Supreme Court nominee -- indicates about how he would do in Thursday's hearing.

During the interview, Kavanaugh denied sexually assaulting anyone. He also denied the account of a second woman, Deborah Ramirez, who told The New Yorker magazine that Kavanaugh caused her to touch his penis at a party when both were Yale freshmen.

Some in the White House expressed relief that Kavanaugh, 53, presented a positive image to counter the allegations. Yet he appeared shaky at times. And there remained concern among aides and Trump himself about how Kavanaugh would hold up facing far fiercer questioning from Senate Democrats, according to a White House official not authorized to speak publicly.

The No. 2 Senate Republican, John Cornyn of Texas, acknowledged that for the nominee "it's extremely awkward to be talking about such private matters on TV." But Cornyn said he thought Kavanaugh "did well and did what he needed to do" in the interview.

Yet Kavanaugh's accounts of his behaviour in high school and college have faced intense scrutiny, with some of his former classmates coming forward to challenge his claims. James Roche, a Yale graduate who says he was Kavanaugh's roommate in 1983, issued a public statement saying he was "close friends" with Ramirez and "cannot imagine her making up" the story about Kavanaugh exposing himself.

While a few Republicans have strongly challenged the credibility of Kavanaugh's accusers, Trump's words have been more biting. Last week, he lampooned Ford's allegation that an inebriated Kavanaugh trapped her beneath him on a bed at a high school house party and tried to take her clothes off before she escaped. Surely she would have reported it to police if the encounter was "as bad as she says," the president said.

"It's a con game they're playing," he said Tuesday. "They're really con artists. They don't believe it themselves, OK?"

Trump's latest broadside was aimed at Ramirez, who conceded to The New Yorker that she'd been drinking at the time she says Kavanagh exposed himself. She also said she was uncertain of some details.

"The second accuser has nothing," Trump told reporters at the United Nations. "The second accuser doesn't even know-- thinks maybe it was him, maybe not. She admits she was drunk. She admits time lapses."

Predictably, that played badly with Democrats.

"How many women have heard that before? How many women have kept their experiences quiet because they knew they would hear that?" Sen. Patty Murray of Washington said of Trump's characterization.

She said Trump's remarks were "disgusting, it's disgraceful and by the way, women are paying attention." She herself was carried to Washington on a 1992 wave of fervour by female voters, a year after the Senate discounted sexual harassment allegations against Clarence Thomas and sent him to the Supreme Court.

In a phone call with Judiciary Committee staff of both parties, Kavanaugh denied Ramirez's story, panel spokesman Foy said.

Ramirez's attorney, John Clune, said his client stood by The New Yorker story and said he and Grassley's committee were trying to decide how to provide more information to the panel. He said an FBI investigation -- which Democrats have also sought for Ford and Trump and Republicans have blocked -- "is the only way to get the truth."

Aides said Kavanaugh answered questions by Judiciary panel staff members about Ramirez's allegations

Republicans are concerned that, win or lose, the battle over Kavanaugh's nomination is further animating women already inclined to vote against Trump's party in November's elections in which control of the next Congress is at stake.

Treatment of Ford, 51, on Thursday will be watched closely.

Sen. Lisa Murkowski of Alaska, a potentially key Republican vote, said GOP senators need to come into the hearing with open minds.

"It's very important to take allegations of those who come forward seriously, and I think we need to go into this hearing with the view that we will listen," she said.

Grassley is planning to use his committee's modest-sized hearing room instead of a far larger chamber that's often home to high-profile hearings. He said in a recent letter that the smaller room would help avoid a "circus atmosphere," and Ford herself has sought to limit the number of TV cameras and journalists covering the event.

Congressional testimony is often magnified by TV close-ups, and a single moment, good or bad, can have a major impact.

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Associated Press writers Kevin Freking, Mary Clare Jalonick, Padmananda Rama, Matthew Daly, Darlene Superville, Jonathan Lemire, Zeke Miller and Deb Riechmann contributed to this report.