U.S. President Donald Trump talks to reporters prior to departing Washington on a campaign trip at Joint Base Andrews in Maryland, U.S., November 5, 2018. REUTERS/Carlos Barria

WASHINGTON (Reuters) - President Donald Trump said on Monday he would nominate a new U.S. ambassador to the United Nations by the end of the week and that more changes in his Cabinet may be coming.

Trump said last week he was seriously considering naming U.S. State Department spokeswoman Heather Nauert to the post to succeed Nikki Haley, who said on Oct. 9 she would resign at the end of the year.

“I’ll announce before the end of the week the U.N. ambassador,” Trump told reporters before leaving Washington for another series of campaign rallies a day before the congressional midterm elections.

“Administrations make changes usually after midterms, and probably we’ll be right in that category, too,” Trump added. “I think it’s very customary. No timeline. For the most part I love my Cabinet. We have some really talented people.”

Haley was the latest in a string of senior Trump administration figures to quit, although she made her announcement in the Oval Office sitting next to Trump, who praised her for doing “an incredible job.”

White House counsel Don McGahn’s departure was announced in August and he has left. Scott Pruitt, the Environmental Protection Agency chief, resigned on July 5 under fire over ethics controversies.

In response to reporters’ questions as he left for a rally in Cleveland, Trump said he was not planning to replace Defense Secretary Jim Mattis. Last month, Trump said Mattis “may leave” and that he regarded him as “sort of a Democrat.”.

He also said Interior Secretary Ryan Zinke was doing a “good job.” Zinke has been under at least three probes by the Interior Department’s inspector general over ethics questions. Last month, the inspector general sent one of the probes to the Justice Department, increasing the chances that Zinke could face a criminal investigation.

Trump did not answer when asked about Attorney General Jeff Sessions, whom he has frequently criticized.