Justices of the US Supreme Court sit for their official group photo at the Supreme Court in Washington, DC, on June 1, 2017. 
Seated (L-R): Associate Justices Ruth Bader Ginsburg and Anthony M. Kennedy, Chief Justice of the US John G. Roberts, Associate Justices Clarence Thomas and Stephen Breyer. Standing (L-R): Associate Justices Elena Kagan, Samuel Alito Jr., Sonia Sotomayor and Neil Gorsuch. / AFP PHOTO / SAUL LOEB        (Photo credit should read SAUL LOEB/AFP/Getty Images)
How are Supreme Court justices chosen?
01:16 - Source: CNN
CNN  — 

Here we go.

President Donald Trump will announce his Supreme Court nominee at 9 p.m. As of this moment, nobody on Capitol Hill knows the selection, according to several senior aides (which, of course, makes sense given the President himself said he hadn’t finalized the selection as of Sunday evening).

Every Senate Republican who wanted to provide their opinion or lobby for a candidate has had an opportunity to do so (and most have taken that opportunity, aides say). Invites have gone out to senators to attend the White House announcement, two aides tell CNN.

But once the selection is made, all that matters is the roughly eight- or nine-week countdown to a vote on the Senate floor.

Bottom line: The coming days will be all about deep dives into the record of Trump’s selection, but also an intensive outside game by affiliated groups in both parties to lock in the contours of what