The Senate is back on Wednesday, and President Trump made his way back to Washington on Monday after laying fairly low to end the year in Palm Beach, Fla., at his personal resort.

His first year was a mixed bag of legislative accomplishments (tax overhaul) and failures (health care); the book is still out on his foreign policy posture; and the Russia probe continues.

So what should we expect in 2018? There are four areas of domestic policy the president is particularly focused on, according to the White House — immigration, infrastructure, welfare and health care.

"I would expect to see those four areas, as well as national security, which never goes away," White House press secretary Sarah Huckabee Sanders said, per USA Today.

More pressingly, there's a Jan. 19 deadline to pass yet another spending bill to keep the lights on in the government.

Here's a look at some of those key priority areas:

National security

The president's team would make the case that the U.S. is safer now and that ISIS is on the run. But there have been lone-wolf attacks domestically on this president's watch, including the truck attack in New York that killed eight people and another man who attempted to blow himself up in the New York subway, but killed no one.

Attacks like this have prompted the president to move to curtail the immigration system further. His critics argue that emboldens recruitment for those trying to pull off or inspire these kinds of attacks. But that will remain an area of political tension.

Iran

The president has tweeted support for protests against the current Iranian regime, while also opposing (yet not completely ripping up) the Iranian nuclear deal.

At least 21 have been reported dead in Iran, as the regime has moved against the protesters. But it's still unclear what this president wants to do tangibly to affect change. Vice President Pence has brought up the difference between past administrations' postures, but remember, back in 2009 when protests also cropped up, it was a very different kind of Iranian leadership that then-President Barack Obama was dealing with. Now, there is a more pragmatic figure in President Hassan Rouhani than Mahmoud Ahmadinejad. So what would change in Iran actually bring?

What's more, Trump's stance on the uprising is more in line with an interventionist approach, which is contradictory to his more isolationist America First policy. So there is a question when it comes to the Trump Doctrine: When does the United States intervene and when does it not? What's the trigger to say, OK, this is where the United States gets involved?

North Korea

Anyone who thought the North Korean leader would be cowed by a more saber-rattling U.S. posture was mistaken. Kim Jong Un took to state airwaves during the New Year's holiday weekend to tout that his country had made progress as a nuclear power — and that he has a button to launch attacks on his desk.

The White House says it remains focused on the "denuclearization" of North Korea. But the president also tweeted criticism of China, a key player in achieving that goal. And, ironically, it is China, which is stepping forward as more of a world leader as the United States has receded, as some see it, under Trump.

China

The view from China of Trump? Yan Xuetong, dean of Tsinghua University's Institute of Modern International Relations, told The New Yorker:

"American leadership has already dramatically declined in the past ten months. In 1991, when Bush, Sr., launched the war against Iraq, it got thirty-four countries to join the war effort. This time, if Trump launched a war against anyone, I doubt he would get support from even five countries. ..."For Chinese leaders, Yan said, 'Trump is the biggest strategic opportunity.' [New Yorker reporter Evan Osnos] asked Yan how long he thought the opportunity would last. 'As long as Trump stays in power,' he replied."

So, for as much as Trump might think President Xi likes him ("He treated me better than anybody's ever been treated in the history of China"), Xi might have a different reason for feeling that way than Trump thinks.

Immigration

As noted, for Trump, immigration is tied to national security. So don't expect him to pull back on his push to curtail various programs and make the U.S. immigration system more merit-based.

Democrats, though, feel like they have leverage in this election year on the issue, especially since there is generally bipartisan support for a DREAM Act or path to legalization if not citizenship for people in the U.S. illegally who haven't committed crimes. (The DREAM Act would provide a path to citizenship for people brought to the United States as children.)

Trump said in September that he was giving Congress six months to address DACA, the executive action implemented by former President Obama on Deferred Action for Childhood Arrivals. That means Congress has until March to do something. DACA allowed people brought to the country as children to avoid deportation. Obama signed the executive order after Congress failed to pass a bipartisan comprehensive immigration overhaul.

"We think we have to have a DACA solution," House Speaker Paul Ryan told NPR's Steve Inskeep on Nov. 30.

We'll see shortly if that's true or what that is. Still, Trump's posture doesn't appear to be one in which a deal has been made. In fact, he tweeted Friday that any DACA deal must include the building of a wall with Mexico, an end to "chain migration" and ending the visa lottery system.

Infrastructure

Infrastructure is always the thing dangled as the potential big area of bipartisanship. Both parties say they want it, and yet nothing has gotten done on it in the past decade.

Why? The question of how to pay for it.

Yet, Trump teased that "maybe we start with infrastructure" in the new year.

"Infrastructure is by far the easiest," the president said Dec. 22 during the bill signing for the tax overhaul. "People want it — Republicans and Democrats. We're going to have tremendous Democrat support on infrastructure as you know. I could've started with infrastructure — I actually wanted to save the easy one for the one down the road. So we'll be having that done pretty quickly."

Having it "done pretty quickly" could be an overstatement. Republicans are going to need 60 votes, which now means nine Democrats with Democrat Doug Jones sworn in Wednesday.

Welfare, entitlements and health care

House Speaker Ryan, R-Wis., has indicated he'd like to target welfare and entitlements, but Trump and Senate Majority Leader Mitch McConnell, R-Ky., are not on board with all that Ryan wants to do.

The Trump administration is reviewing the programs, and the White House is preparing a January executive order related to welfare, according to Politico. NPR's Mara Liasson reports the president "wants to keep his promise not to touch the big, middle-class entitlements — Medicare and Social Security — but he is interested in reforming means-tested programs that target lower-income Americans."

Temporary Assistance for Needy Families, or TANF, affects about a million and a half families. And, Liasson reports:

"White House aides say they are now looking at a number of additional changes, including tighter work requirements and drug-testing rules for food stamps, Medicaid and housing assistance. Those changes may not save much money the way changes in the big middle-class entitlements like Medicare or Social Security might. But it will help the president highlight an issue that seems to motivate his base in a year when getting Republican voters excited is the No. 1 goal."

The Senate looks less-than enthused to change any of the big entitlements, too. McConnell, who will be clinging to an even narrower 51-49 majority in 2018, told Axios he "would not expect to see" the Senate work on making changes to those programs without Democrats.

"I think entitlement changes, to be sustained, almost always have to be bipartisan," McConnell told NPR. "The House may have a different agenda. If our Democratic friends in the Senate want to join us to tackle any kind of entitlement reform, I'd be happy to take a look at it."

Translation: He's not about to walk the plank without holding hands with Democrats — and Democrats aren't going anywhere near the edge of that ship.

It's the same story when it comes to health care.

"Well, we obviously were unable to completely repeal and replace with a 52-48 Senate," McConnell told NPR. "We'll have to take a look at what that looks like with a 51-49 Senate. But I think we'll probably move on to other issues."

Does Ryan resign?

So if a tax overhaul has passed — and Ryan can't get his next agenda on entitlements, welfare or health care through the Senate, it does raise the question — does he think about stepping aside in the next few months or after the election?

Remember, this is not a job he wanted. He was seen as the only one who could get the votes to become speaker after John Boehner resigned. It's certainly been rumored that Ryan is considering resigning — and it makes some sense. At this point, it's just speculation, but worth watching.

"I ain't goin' anywhere," Ryan told reporters after a Politico piece speculating on his resignation came out Dec. 14.

His office added, "This is pure speculation." Spokeswoman AshLee Strong said, "As the speaker himself said today, he's not going anywhere any time soon."

Boehner's spokespeople denied he was leaving up until right before he did.

Midterms will shape the year

Not much traditionally gets done in midterm years, McConnell is skittish about diving into the president's thornier priorities, and Democrats feel they have some leverage now on things like immigration and infrastructure.

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