Brett Kavanaugh moved to the brink of a lifetime appointment to the U.S. Supreme Court Friday as a bitterly divided Senate voted to advance President Donald Trump's nominee following weeks dominated by allegations of sexual misconduct, questions about the scope of an FBI investigation and concerns over whether the confirmation fight itself has damaged public confidence in the nation's highest court.

The Senate voted 51–49 to end debate on Kavanaugh's nomination, clearing the final major procedural obstacle before a confirmation vote expected Saturday.

Nearly every Republican supported advancing the nomination. Republican Sen. Lisa Murkowski of Alaska broke with her party and voted no, while Democratic Sen. Joe Manchin of West Virginia joined Republicans in voting yes.

But the vote represents much more than another partisan battle over a Supreme Court seat.

Kavanaugh's confirmation could reshape the ideological balance of the Supreme Court for decades.

And the circumstances surrounding his nomination have made the fight one of the most contentious Supreme Court confirmation battles in modern American history.

The Allegation That Changed the Confirmation

Kavanaugh's nomination initially appeared headed toward a conventional partisan confirmation fight.

That changed dramatically when Christine Blasey Ford publicly accused Kavanaugh of sexually assaulting her when the two were teenagers in the early 1980s.

Ford alleged that Kavanaugh pinned her to a bed during a gathering, attempted to remove her clothing and covered her mouth when she tried to scream.

Kavanaugh categorically denied the allegation.

Both appeared before the Senate Judiciary Committee on September 27 in testimony watched across the country.

Ford told senators she was certain Kavanaugh was the person who assaulted her.

Kavanaugh responded with an emotional and angry denial, telling senators that he had never sexually assaulted Ford or anyone else.

He accused opponents of orchestrating an effort to destroy his reputation and his nomination.

The hearing did little to settle the dispute.

Instead, it intensified it.

More Allegations Surface

Ford was not the only woman to make allegations against Kavanaugh.

Deborah Ramirez, a Yale University classmate, alleged that Kavanaugh exposed himself to her during a college gathering.

Kavanaugh denied that allegation as well.

Other allegations also emerged during the confirmation process. Kavanaugh denied wrongdoing, and some claims received substantial scrutiny regarding their credibility.

Republicans argued that accusations unsupported by corroborating evidence should not be permitted to destroy a nominee's reputation or prevent his confirmation.

Democrats countered that the Senate was rushing toward a lifetime appointment without sufficiently investigating serious allegations.

The result has been a confirmation process in which senators are not merely debating Kavanaugh's judicial philosophy.

They are debating what happened decades ago — and whether enough has been done to find out.

FBI Investigation Draws Criticism

The controversy prompted Republican Sen. Jeff Flake of Arizona to call for an additional FBI background investigation before the Senate proceeded with Kavanaugh's nomination.

The White House authorized the supplemental investigation, which was completed this week.

Republicans reviewing the confidential FBI material said investigators had found no new corroborating evidence supporting the allegations against Kavanaugh.

Democrats reached a very different conclusion about the investigation itself.

They complained that investigators were operating under restrictions that prevented them from interviewing some people who claimed they possessed relevant information.

Ford and Kavanaugh themselves were not interviewed again by the FBI during the supplemental investigation.

Critics therefore argue that the investigation cannot reasonably be described as comprehensive.

That distinction is important.

A failure to uncover corroborating evidence is not necessarily the same thing as establishing that an allegation is false.

Republicans maintain that Kavanaugh deserves the presumption that unproven allegations should not prevent him from serving on the Supreme Court.

Democrats argue that the Senate's responsibility is not equivalent to determining criminal guilt beyond a reasonable doubt. They say senators must instead decide whether unresolved questions are acceptable when considering someone for a lifetime appointment to the nation's highest court.

Questions About Kavanaugh's Temperament

The sexual misconduct allegations are not the only issue now surrounding the nomination.

Kavanaugh's performance during the September 27 hearing has generated a separate debate over judicial temperament.

During his testimony, Kavanaugh angrily condemned the accusations and accused Democrats of participating in a politically motivated effort to destroy him.

He described the confirmation fight as a calculated political attack fueled partly by anger over Trump's 2016 election and retaliation connected to investigations involving the president.

Supporters saw an innocent man furious over what he regarded as false accusations that threatened his career and family.

Critics saw something more troubling in a prospective Supreme Court justice: overt partisanship, hostility toward senators questioning him and rhetoric that could raise questions about whether he could approach politically sensitive cases impartially.

That question could remain long after the confirmation fight ends.

Supreme Court justices do not serve fixed terms.

They can remain on the bench for decades.

A Court That Could Move Rightward

The stakes surrounding Kavanaugh extend far beyond the allegations against him personally.

Trump nominated Kavanaugh to replace Justice Anthony Kennedy, who frequently served as a pivotal vote in closely divided cases.

Kavanaugh's confirmation could create a durable five-member conservative majority on the nine-member court.

That could influence American law for a generation.

Cases involving abortion rights, voting rights, gun laws, environmental regulations, executive power, labor unions, campaign finance and the separation of church and state could eventually come before a court with Kavanaugh sitting on it.

For opponents, that makes concerns about the confirmation process particularly serious.

A senator who serves six years can be replaced at the next election.

A president serves four years before facing voters again.

A Supreme Court justice can remain in power for 20, 30 or even 40 years.

There is no regular election and no ordinary mechanism for voters to reverse the appointment.

Questions About Presidential Power

Kavanaugh's views concerning presidential authority have also attracted scrutiny because he is being nominated by a president facing ongoing investigations.

As a federal judge and legal scholar, Kavanaugh has previously written about the burdens that criminal investigations and civil litigation can impose upon sitting presidents.

Critics have questioned how he might rule if disputes involving Special Counsel Robert Mueller's investigation or other attempts to investigate Trump eventually reach the Supreme Court.

Kavanaugh has said he would approach cases independently and follow the Constitution and existing law.

Nevertheless, Democrats have argued that confirming Trump's nominee while investigations involving the president remain active creates an unavoidable concern about how future disputes involving presidential power could be decided.

Collins Announces Support

The nomination received a major boost Friday afternoon when Republican Sen. Susan Collins of Maine announced that she intends to vote for Kavanaugh.

Collins had been one of the most closely watched undecided senators.

In a lengthy Senate speech, she said the allegations against Kavanaugh were serious but concluded that they had not been sufficiently corroborated to justify rejecting his nomination.

Murkowski reached the opposite conclusion.

The Alaska Republican said Kavanaugh was not the right person for the Supreme Court at this time.

Their disagreement illustrates the extraordinary difficulty of the decision facing senators.

A Lifetime Decision

Saturday's expected confirmation vote will determine whether Brett Kavanaugh becomes the 114th justice of the United States Supreme Court.

But whatever happens, the battle surrounding his nomination is unlikely to disappear when senators cast their votes.

If Kavanaugh is confirmed, he will join the Court carrying the legacy of one of the most divisive confirmation proceedings in its history.

Supporters will see a qualified federal judge who survived allegations they believe were never adequately substantiated.

Opponents will see a lifetime appointment approved despite unresolved allegations, a disputed investigative process and serious questions about the nominee's temperament and impartiality.

And because Supreme Court appointments can shape American law long after the presidents and senators responsible for them have left office, the consequences of this vote could last for decades.

The Senate is now one vote away from making that decision permanent.

Source: U.S. Senate records, Senate Judiciary Committee materials and contemporary reporting on the Kavanaugh confirmation proceedings.