WASHINGTON (AP) — The Latest on President Donald Trump and Republican senators (all times local):

7:50 a.m.

Sen. Bob Corker says the White House should "step aside" and let Congress' tax-writing committees figure out how to pay for the $1 trillion tax cut President Donald Trump wants to sign by the end of the year.

The Tennessee Republican tells NBC's "Today" Tuesday that the tough, "spinach part" of the process is looming and suggests that recent White House decisions to take proposals off the table aren't helping. On Monday, Trump ruled out changes to popular 401(k) retirement plans to help pay for the tax cut.

Corker, who has announced plans to retire and has been critical of Trump, says he hopes the White House will let the committees do their work in a "normal process."

Trump heads to the Capitol on Tuesday to join Senate Republican lawmakers at their weekly policy luncheon.

On another topic, Corker, the Senate Foreign Relations chair, says Trump's tweets and heated rhetoric on North Korea have raised tensions and undercut Secretary of State Rex Tillerson's diplomacy. "When you kneecap that effort," Corker says, "you really move our country into a binary choice, which could lead to a world war."

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3:40 a.m.

President Donald Trump is planning lunch with GOP senators on Capitol Hill as congressional Republicans turn their focus to overhauling the tax code.

It's to be Trump's first appearance as president at the Senate Republicans' regular Tuesday policy lunch. It comes as Trump has sparred with GOP senators such as John McCain of Arizona and Bob Corker of Tennessee, as well as with Majority Leader Mitch McConnell — though McConnell and Trump had a joint press conference last week to try to smooth things over.

So the lunch has potential for awkward moments. Nonetheless, Republicans and the Trump administration are determined to get tax legislation into law this year, and all sides seem to think they can unite around that goal.