Liberals also took issue with the presence of Leonard Leo, the Federalist Society's executive vice president, who is now on leave from the group of conservative attorneys and scholars to work with Trump's Supreme Court nomination team.
Democrats in the past also have pointed to Kavanaugh's work for Bush during the recount fight in the pivotal state of Florida in the 2000 presidential election, a controversy that was resolved only after the conservative-majority Supreme Court sided with Bush over Democratic candidate Al Gore, settling the election outcome.
The Judicial Crisis Network (JCN), whose leaders pushed Justice Neil Gorsuch over the finish line a year ago, are getting their war chests ready.
Trump, meanwhile, said that he does not ask about a nominee's "personal opinions".
The president has spent the days leading up to his announcement discussing the pros and cons of the various options with aides and allies. But Senate Democrats held up his confirmation for three years, accusing him of being a Bush political operative.
A confirmation would solidify the Supreme Court's conservative majority and continue President Trump's push to shift the federal bench to the right. Hardiman, who lives in Pennsylvania, is a judge on the U.S. Court of Appeals for the 3rd Circuit, where he served at one time with Trump's sister, Judge Maryanne Trump Barry.More news: Southgate’s World Cup waistcoats just the right fit for London museum
Reportedly, Louisiana State University law professor Ken Levy suggested that Democratic politicians should sue Republican Senate Majority Leader Mitch McConnell over the Senate judicial confirmations process to hold them accountable for stalling Obama's nominee in 2016. Barry served alongside Hardiman as a federal appeals judge on the 3rd Circuit before stepping down past year.
The White House invited a number of senators to attend the Monday night announcement, including Judiciary Committee Chairman Chuck Grassley, R-Iowa, and committee member Kennedy. The Supreme Court nominee argued in the past that President Bill Clinton could have been impeached for lying to and misleading both his staff and the public at large.
Those views could have implications for independent counsel Robert Mueller's investigation of President Trump.
Liberal Democratic Senator Bernie Sanders said in a tweet that if Kavanaugh is confirmed "it will have a profoundly negative effect on workers' rights, women's rights and voting rights for decades to come".
Bob Casey (D-Pa.), who opposes abortion, announced on Monday he can not support a process that involved Trump's picking from a list of 25 candidates selected by conservatives and big business.
Kennedy had voted to preserve the core principles of the high court's 1973 ruling in Roe v. Wade.
The Judicial Crisis Network is planning a $1.4 million ad buy in Alabama, Indiana, North Dakota and West Virginia - states with moderate Democratic senators who could be pressured to vote for Trump's nominee. The Trump team, facing its own Mueller investigation, has looked into that part of Mr Kavanaugh's resume, according to CNN's White House correspondent Jim Acosta. This may also not be Trump's last opportunity to appoint to the highest court in the United States: Justice Ruth Bader Ginsberg is 85, and Justice Stephen Breyer turns 80 in August.