WASHINGTON — Eight years ago, a vocal minority of Republicans peddled the conspiracy theory that Barack Obama wasn’t born in the United States.

Now that the lead proponent of that debunked idea is the president of the United States and the head of the Republican Party, conspiracy theories have now gone mainstream inside the GOP.

The latest example: Sen. Ron Johnson, R-Wis., appearing to argue on “Meet the Press” yesterday that the real interference in the 2016 election was from Ukraine.

“And so what President Trump's had to endure, a false accusation — by the way, you've got John Brennan on -— you oughta ask Director Brennan what did Peter Strzok mean when he texted Lisa Page on December 15th, 2016?” Johnson said.

He added, “What he wants is he wants to — an accounting of what happened in 2016. Who set him up? Did things spring from Ukraine?”

Also: “You know, there's a good piece. We've got an oversight letter on, from Politico in 2017 where, let me quote the article, it says, 'Ukrainian government officials tried to help Hillary Clinton and undermine Trump.'”

And: “I don't know to what extent DNC and Hillary Clinton campaign were involved in kinda juicin' up the — the Ukrainian involvements as well.”

What spurred this response from Johnson? The first question he received on the show about his concern to the Wall Street Journal that military aid to Ukraine and investigations might be combined.

Later in the interview, Johnson did admit that Russia interfered in the 2016 presidential election, and he also agreed that former Trump campaign chair Paul Manafort wasn’t framed for his convicted crimes.

Still, he wasn’t the only other mainstream Republican over the weekend talking about Ukraine and the 2016 election.

Here’s Secretary of State Mike Pompeo, who was Trump’s former CIA director and a former Republican congressman from Kansas:

“And it is not only appropriate, but it is our duty to investigate if we think there was interference in the election of 2016, I think everyone recognizes that governments have an obligation — indeed, a duty — to ensure that elections happen with integrity, without interference from any government, whether that’s the Ukrainian government or any other.”

“The Republican Party has got to get a grip on itself," Colin Powell said. "Republican leaders and members of the Congress, both Senate and the House, are holding back because they're terrified of what will happen to any one of them if they speak out."

Tweet of the day

virtually every elected republican right now is either a fan of trump or trembling in terror of the ratio https://t.co/JrbH4yXuP3 — b-boy bouiebaisse (@jbouie) October 6, 2019

U.S. withdraws from northern Syria before Turkish operation

And as Trump deals with an impeachment inquiry back home:

“The U.S. military has moved its forces away from the Turkish border with northern Syria, after the White House said Sunday night that Turkey would soon begin an operation in a part of northeastern Syria where it wants to resettle Syrian refugees — and that U.S. forces wouldn't be there to help or stop them,” per NBC News.

Why this is significant: “The announcement is a major blow to the Kurdish-led Syrian Democratic Forces, or SDF, which the United States relied upon heavily as the most effective fighting force against ISIS and the reaction from Kurds so far has been one of anger.”

The other international-domestic story worth paying attention to concerns the NBA.

Just because this is the NBA doesn’t mean it’s serious. A lot of Fortune 500 companies are probably paying very close attention. And are nervous.

Bernie Sanders had a heart attack — and how it could reshape the Dem race

Three years ago, the political world flipped out after Hillary Clinton had a fainting spell on 9/11.

As it turned out, she had pneumonia.

But on Friday afternoon, we learned that what caused Bernie Sanders to have an emergency heart procedure was a heart attack.

And it took the campaign three whole days to let the public know that.

In addition to reminding the public that the three top Democratic presidential candidates are 70 and older, the Sanders news could reshape the Dem race – at least at the margins – with the Vermont senator sitting in third place in most 2020 Dem polls.

2020 Vision: Two strong polls for Biden

Despite all the negativity surrounding his campaign, Joe Biden received two good Fox polls over the weekend.

In South Carolina, the poll shows Biden ahead by nearly 30 points, an increase since July: Biden 41 percent, Warren 12 percent, Sanders 10 percent, Harris 4 percent, Steyer 4 percent, Booker 3 percent.

And in Wisconsin, the Fox poll has Biden narrowly ahead of Warren in the Dem race – and leading Trump in the general in that state by almost 10 points.

On the campaign trail today: Cory Booker spends his day in Iowa… So does Kamala Harris… Julian Castro visits a refugee camp in Brownsville, Texas… And Michael Bennet campaigns in New Hampshire.

Dispatches from NBC’s embeds

Cory Booker yesterday campaigned in Iowa where, per NBC’s Priscilla Thompson, the senator saw a better response than Dem Montana Gov. Steve Bullock did: “Folks were packed in tight here and Booker got robust laughs, claps and audible responses from this crowd. Gov. Steve Bullock hosted an event here weeks ago to a far smaller crowd.” Booker also took a small swipe on candidates campaigning on plans, plans, plans (wink wink, Elizabeth Warren): “Nobody wins presidential elections based upon who has a better 15-point policy plan on guns, even though I believe I do have one. The reality is though, we've lost elections before. … It has not just do with the head, it's the heart and the spirit and where our country is.”

Over the weekend, eight Democratic hopefuls spoke at the SEIU presidential forum in California where NBC’s Benjamin Pu covered how the candidates spoke to labor-focused issues. Read his full recap here. Per Pu, “While all candidates spoke at length about labor issues and their personal connections to unions, some of the biggest responses they got from SEIU members came from their answers on immigration, ending mass incarceration, and health care.”

Data Download: The number of the day is … 9 points

9 points.

That’s Joe Biden’s margin over Donald Trump in a hypothetical matchup in Wisconsin, according to a new Fox News poll.

The poll found that Biden leads Trump in the Badger State 48 percent to 39 percent. That’s compared with Bernie Sanders besting Trump by 5, 45 percent to 40 percent, and Elizabeth Warren up 45 percent to 41 percent — both results within the poll’s margin of error.

Talking policy with Benjy

There’s been a whole lot of talk about the “Overton window” this cycle as progressive and socialist activists push for bigger and bigger plans that, beyond their individual merits, serve to make the previous leftward position seem more mainstream by comparison, NBC’s Benjy Sarlin observes.

We may be seeing something similar happening under the radar on guns, a topic where nine of the Democratic candidates met for an MSNBC forum hosted by March For Our Lives and Gabby Giffords last week.

The big Overton-Window-moving policy in this debate is Beto O’Rourke’s call for a mandatory buyback of assault weapons, an idea modeled on Australia’s gun laws that had zero buy-in from the major players in the gun debate until recently.

Far more quietly, though, an alternative approach is also gaining ground: Requiring all owners of assault weapons to register their guns with the ATF and pass a background check. The approach is similar to how old machine guns are regulated, which are rarely associated with crimes. Joe Biden made it a key part of his own gun plan, which he released on Wednesday. Senators Elizabeth Warren and Bernie Sanders have backed the idea this cycle as well.

Four years ago, this approach would have been a boundary-pushing position, as gun rights activists are strongly opposed to any policy that involves registration of individual firearms. It’s still untested in a general election, but thanks to the mandatory buyback push, it’s suddenly the “moderate” position among the top tier Democrats. That’s a big shift.

The Lid: Bernie and Biden’s bad week

Don’t miss the pod from Friday, when we observed that Bernie Sanders and Joe Biden were probably glad that the Ukraine/whistleblower/impeachment story dominated the political news last week.

ICYMI: News clips you shouldn’t miss

The attorney for the original Ukraine phone call whistleblower now says his team now represents “multiple” officials.

The Supreme Court is set to take up gay rights, DACA and religious freedom this term.

What exactly is happening with the Ukrainian promise to “audit” previous corruption cases?

Benjy Sarlin writes that other Democrats are worried that they could face the same treatment that Biden is getting from Trump now.

Trump Agenda: Paralyzing

The Washington Post writes that many GOP lawmakers are “paralyzed” by the impeachment inquiry.

Here’s what we know about the U.S. preparations to withdraw from northern Syria.

Jane Timm fact-checks Trump’s baseless Biden/China conspiracy theory.

The New York Times looks back at how past presidents swore off soliciting or accepting any kind of political help from other countries.

2020: Recovering in Vermont

Bernie Sanders is recovering from his heart attack at home in Vermont.

And Sanders is out with a new campaign finance plan.

ICYMI: Joe Biden in a Washington Post op-ed: “Trump won’t destroy me, and he won’t destroy my family.”

How is impeachment playing in swing districts? The AP checks in.

Pete Buttigieg has a new prescription drug plan.

Trump has managed to alienate some important voting blocks in Florida, POLITICO writes.

Kamala Harris says that Iowa’s caucuses can prove her electability argument.

What does impeachment mean for Susan Collins in 2020?