First Read is your briefing from Meet the Press and the NBC Political Unit on the day's most important political stories and why they matter.

The brutal truth about American politics: One day, you're considered a brilliant politician and a master tactician. The next — you're a loser who’s getting squeezed from both sides of your party.

That is Senate Majority Leader Mitch McConnell's story after his terrible Tuesday. To recap:

McConnell and his leadership team surrendered on their latest effort to repeal and replace Obamacare, saying they didn’t have the votes to pass it;

One of the top senators from the “Governing Wing” of the Republican Party, Sen. Bob Corker, Tenn., announced he wouldn’t seek re-election, potentially (and we stress that word) putting that Senate seat in play;

And then in the evening, McConnell’s preferred candidate in Alabama’s GOP Senate runoff, appointed Sen. Luther Strange, lost by 10 points to controversial conservative Roy Moore, 55 percent to 45 percent.

To make Tuesday even worse for McConnell, his beloved Louisville Cardinals are now caught up in a college basketball scandal.

But bigger than that rough day is the fact that McConnell is now getting pressure from two different sides — from rank-and-file senators who’ve been upset at the (mostly) partisan approach that the Senate majority leader has taken, as well as from GOP grassroots conservatives, who don’t think that McConnell has done enough to support Trump’s agenda. That’s a no-win situation.

One of McConnell’s top political attributes is that he’s a survivor, and that he knows how to adjust. But right now, he’s facing arguably his greatest challenge — being the Senate majority leader (with a bare majority) in the Trump Era.

And like that – he’s gone: Trump deletes past tweets in support of defeated Luther Strange

McConnell, of course, wasn’t the only loser on Tuesday — so was Trump, who backed Strange and campaigned for him on Friday. And get this: Trump DELETED his recent pro-Strange tweets, according to ProPublica. Here’s what he deleted:

Big election tomorrow in the Great State of Alabama. Vote for Senator Luther Strange, tough on crime & border — will never let you down!

Luther Strange has been shooting up in the Alabama polls since my endorsement. Finish the job - vote today for "Big Luther."

ALABAMA, get out and vote for Luther Strange - he has proven to me that he will never let you down! #MAGA

Oof. And the president tweeted this last night and this morning:

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Congratulations to Roy Moore on his Republican Primary win in Alabama. Luther Strange started way back & ran a good race. Roy, WIN in Dec!

Spoke to Roy Moore of Alabama last night for the first time. Sounds like a really great guy who ran a fantastic race. He will help to #MAGA!

Say what you will about McConnell’s rough Tuesday, but at least he didn’t pretend like he never supported Luther Strange.

Meet Roy Moore

Looking ahead to the December 12 general election between Republican Roy Moore and Democrat Doug Jones, Moore will be the big favorite given that Alabama went for Trump, 62 percent to 34 percent in 2016. But Democrats have the opportunity to score points on Moore’s past controversies, which include:

In 2001, as chief justice, Moore installed a 5,280-pound granite Ten Commandments monument in the rotunda of the Alabama Supreme Court — during the night, without telling his fellow justices. "I'm the highest legal authority in the state, and I wanted it there," he said of the decision. The move prompted the long legal battle that would result in his first removal from the court.

In 2002, he wrote an opinion in a child custody case stating that homosexuality is “an inherent evil,” and “abhorrent, immoral, detestable, a crime against nature and a violation of the laws of nature and of nature's God.”

In November 2003, the Alabama Court of the Judiciary ousted Moore from office for refusing to follow a federal court order to remove the Ten Commandments monument. He remained unapologetic, saying “I'd do it all the same all over again.”

In 2006, he wrote that Rep. Keith Ellison, D-Minn., shouldn’t serve in Congress because he’s Muslim.

In 2012, Moore said at a Tea Party rally that same-sex marriage would be “the ultimate destruction of our country because it destroys the very foundation upon which this nation is based."

After a federal judge struck down Alabama’s same-sex marriage ban, Moore advised state probate judges not to issue marriage licenses to same-sex couples despite the ruling.

Per CNN, Moore’s foundation shared a video in 2015 that promoted the conspiracy theory that Barack Obama is a Muslim.

In 2016, after the Supreme Court legalized same-sex marriage nationwide, Moore again issued an order directing state probate judges to continue enforcing the same-sex marriage ban in the state. As a result, the Alabama Judicial Inquiry Commission suspended him from his post for the remainder of his term.

Earlier this year, Moore called Islam a “false religion” and said of Vladimir Putin’s views on gay rights “Well, maybe Putin is right. Maybe he’s more akin to me than I know.”

As Stu Rothenberg observed, “Corker out. Moore in. Tells you all you really need to know.” That’s your Republican Party of 2017.

As for Democrats, we get that they have performed better in under-the-radar races (see the state legislative victories below) than in full-blown nationalized contests (like GA-6 and MT-AL). But they have a win-win opportunity in contesting Alabama: Go in for Doug Jones and pull off a Scott Brown-like upset, or lose but turn Roy Moore into a household name in two months. Major political parties can’t ignore Senate races in an unfavorable part of the country.

Democrats have a (slight) opening in Tennessee

As for Corker’s retirement, it creates an open seat that certainly favors Republicans. Tennessee, after all, is hardly hospitable ground for Democrats — Trump won the state 61 percent to 35 percent in 2016. But Corker deciding not to run for re-election gives Democrats an opening to make the 2018 Senate race in the state competitive.

Right now, there are two high-profile Democrats running for governor — former Nashville Mayor Karl Dean and state House Minority Leader Craig Fitzhugh. If one of these Democrats decides to run for the Senate race, that could potentially put Tennessee on the 2018 map, despite the Democrats’ poor performance in federal statewide races there. (The closest Democrats have gotten to winning in one of these federal statewide races was in 2006, when Corker barely beat Harold Ford Jr., 51 percent to 48 percent.)

Dems pick up seats in two state special elections

While most eyes were on Alabama’s Senate runoff last night, two state special elections last night shouldn’t be overlooked — and they held good news for Democrats. In the Miami area, Democrat Annette Taddeo beat state representative (and former Apprentice candidate!) Jose Felix Diaz to pick up a closely-contested state Senate seat.

The area was carried by Hillary Clinton in 2016, but the seat was last won by a double-digit margin by Republican Sen. Frank Artiles, who was forced to resign after making racist remarks. (Republicans did hang on to Diaz’s House seat, which he had to vacate to run against Taddeo.)

More surprising than the Florida win, however, was Democrats’ upset in a New Hampshire House race, where first-time candidate Kari Lerner snagged a formerly GOP-held seat in an area won by Donald Trump by nearly 20 points in 2016. The victories make a total of eight state legislative seats flipped from red to blue this cycle.

Millennial Poll: Democrats can’t take their vote for granted

"Millennials overwhelmingly disapprove of the way President Donald Trump is handling his job and they don't have a favorable view of the Republican Party. But Democrats shouldn't celebrate just yet, according to results from the first NBC News/GenForward Survey," Hannah Hartig, John Lapinski and Stephanie Perry write.

"A majority of millennials, 64 percent, disapprove of Trump's job performance, while 58 percent said they have an unfavorable view of the Republican Party. The survey was conducted Aug. 31-Sept. 16 among a nationally representative sample of 1,816 adults aged 18-34."