(CNN) The Supreme Court nomination of Brett Kavanaugh took a major step forward on the Senate floor Friday morning, as 51 senators voted to end debate in the chamber and move toward a vote on final confirmation on Saturday.

That vote was a massive boost for Kavanaugh, Senate Majority Leader Mitch McConnell and President Donald Trump, who had privately fretted since allegations of sexual assault against the judge were revealed two weeks ago that he might not make it to even this point.

And to be clear, "this point" is not the end point. Voting for an end to the endless debate that defines the Senate is not the same thing as voting for Kavanaugh's final confirmation.

But, make no mistake: The cloture vote was seen as an absolutely key test of Kavanaugh's strength among the four undecided Senators -- Republicans Susan Collins of Maine, Jeff Flake of Arizona and Lisa Murkowski of Alaska, as well as Democrat Joe Manchin of West Virginia -- who had (and have) the ability to make or break the nomination.

In the end, three of those four undecideds -- Collins, Flake and Manchin -- voted to end debate. Murkowski opposed it.

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