Kavanaugh, the conservative appellate court judge and President Donald Trump's choice to replace retiring Justice Anthony Kennedy, was meeting separately with at least five members of the Judiciary Committee. The panel will launch confirmation hearings later this summer.
Republican Sen. Orrin Hatch of Utah, who had conferred with Trump on making his second pick for the court, called the Yale-educated judge "a very fine man" and told reporters he expects Kavanaugh's confirmation to go well.
"There will be the usual attempts to sully his reputation, not only in the Senate but outside the Senate, but he'll be able to handle it, and I have every confidence he'll be confirmed," Hatch said.
But Kavanaugh has an unusually long paper trail for senators to review, including judicial rulings and documents from his tenure in the George W. Bush administration and on Kenneth Starr's investigation of President Bill Clinton. Aides say it could take weeks to assemble those materials.
Democrats, as the Senate minority, have few options to block Kavanaugh. But they can use the time to make the case that confirming Kavanaugh will tilt the court too far to the right. They warn that Kavanaugh could be part of majority decisions rolling back women's access to abortion and undoing aspects of the Affordable Care Act.
Democrats are also raising red flags over Kavanaugh's past writing that suggests investigations of sitting presidents are a distraction to executive branch leadership. They see that as concerning amid the special counsel's investigation into Russian interference in the 2016 election and Russian ties to the Trump campaign.
"The American people should have their eyes wide open to these stakes," said Sen. Chuck Schumer, D-N.Y., the minority leader.
No date has been set for confirmation hearings. But Sen. John Cornyn, R-Texas, who also met with Kavanaugh on Wednesday - and, as a former attorney general, once worked with him during practice for a session before the court - said he was hopeful the committee could begin its work during the final week of August.
Republicans want to have Kavanaugh confirmed by the start of the court's session in October and before the midterm election.
Cornyn acknowledged Trump's choice of the judge was "a little bit of a calculated risk ... because Judge Kavanaugh has the longest paper trail" of any potential nominee. Kavanaugh was first confirmed to the appellate court in 2006.
On the other hand, Cornyn said, Trump should be congratulated for nominating somebody whose record is so long that "people can evaluate on their own, fairly."
Both sides have begun airing ads and mobilizing voters for a long summer confirmation battle that will stretch into the fall.
Because Republicans hold a slim majority, 51-49, narrowed further by the absence of GOP Sen. John McCain of Arizona, almost every vote matters. About 10 key senators - two or three Republicans and a half dozen Democrats - are facing intense pressure over their votes.
Republicans are pushing for a bipartisan showing of support for Kavanaugh by trying to peel off Democrats who are up for re-election from Trump-won states. That group includes Sen. Joe Donnelly of Indiana, Sen. Heidi Heitkamp of North Dakota and Sen. Joe Manchin of West Virginia, who all voted for Trump's initial Supreme Court pick, Neil Gorsuch, last year.
But so far, Democrats are holding back. They view the uphill battle against Kavanaugh as similar to their successful fight last summer to preserve the health care law from a Republican repeal effort.
As part of that strategy, Democrats are focusing on Republicans Susan Collins of Maine and Lisa Murkowski of Alaska, who both helped doom the repeal of the health care law.
Democrats warn that with GOP-backed lawsuits to unravel "Obamacare" headed to the court, Americans are again facing threats to undo protections for people with pre-existing conditions. The two GOP senators also support access to abortion services.
"We won this battle in the light of day last year," said Sen. Chris Van Hollen, D-Md. "We need the American people to weigh in."
While Kavanaugh was meeting with senators, environmental groups slammed his record on the District of Columbia Court of Appeals, which handles many regulatory cases. Activists said he represents a grave threat to bedrock environmental laws that protect clean air and water and endangered species.
Michael Brune, executive director of the Sierra Club, the nation's largest environmental group, said Kavanaugh "continually and reliably sides with corporate polluters and the wealthy over the public's right to breathe clean air and drink clean water."
Brune and other critics cited a 2014 opinion in which Kavanaugh argued that the Environmental Protection Agency must take monetary costs into consideration when deciding whether to regulate mercury and other pollutants from power plants.
The court majority agreed with EPA that it did not have to consider costs in protecting health and safety.
In his dissent, Kavanaugh wrote that it came as a "surprise" that the EPA did not consider costs and said the agency's failure to do so was "unreasonable," citing significant costs for industry to meet the regulations.
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