Washington - Barely arrived in the White House, President Donald Trump has touched off a stormy debate over the extent of his popular support, but sought on Sunday to shift the focus to upcoming actions from his office. A day after massive anti-Trump protests in Washington and in hundreds of towns and cities around the world, the new president turned to Twitter to mock the demonstrators who had filled the streets."Why didn't these people vote? Celebs hurt cause badly," Trump tweeted early on Sunday, referring to the actors, singers, writers and filmmakers who took the stage at the Washington march to speak out against him.An hour later, adopting a more conciliatory tone, he tweeted that "peaceful protests are a hallmark of our democracy.""Even if I don't always agree," he said, "I recognise the rights of people to express their views."More than two million people are estimated to have taken part in the women-led marches in the US and around the world to defend women's rights and oppose an array of policy stances from the new president.Trump was facing unfavourable comparisons to his inauguration attendance a day earlier, and on Saturday accused the news media of lying about the turnout at his swearing-in."It looked like a million, million and a half people," he said, adding that "all the way back to the Washington Monument was packed."White House press secretary Sean Spicer also lashed out at media that published photos showing the crowd was far from reaching the monument - calling their reporting "shameful." Trump's numbers 'obsession'Burned by past controversies, Washington authorities no longer estimate crowd sizes.However, analysis of aerial photos and Metro usage numbers from the city's transit authority showed beyond doubt that Trump's inauguration crowd was far smaller than the turnout for Barack Obama's 2009 swearing-in.Trump aides were on the defensive on Sunday when asked about the administration's preoccupation with crowd size. Senior aide Kellyanne Conway was asked on NBC why Trump sent out his spokesperson to convey a "provable falsehood" about the turnout. She replied: "Sean Spicer gave alternative facts."That statement caused a huge response on Twitter, with mocking comments about #alternativefacts trending to the top in the United States and to the second-highest spot worldwide. Looking aheadConway and Spicer sought on Sunday to shift the focus to the days ahead. They noted that the Republican president has a hectic schedule for the week, including plans to sign several executive orders to carry out campaign promises. The new president spoke on the phone Sunday with Israeli Prime Minister Benjamin Netanyahu. The two discussed "threats posed by Iran" and agreed that peace between Israel and the Palestinians must be "negotiated directly," the White House said in a statement.On Thursday, Trump will meet with Republican members of Congress in Philadelphia.The following day, he will host British Prime Minister Theresa May - the first White House visit of a foreign leader under the new administration.Trump on Sunday also pledged to begin renegotiating the North American Free Trade Agreement in upcoming talks with the leaders of Mexico and Canada.On the campaign trail, Trump called NAFTA the worst trade deal the United States has ever signed and vowed to renegotiate or rip it up.Tillerson gets key supportWith only two of his cabinet nominees confirmed so far by the Senate, Trump received good news about his pick to head the powerful State Department, former ExxonMobil chief Rex Tillerson. Two leading Republican senators, Lindsey Graham and John McCain - both of whom had expressed reservations about Tillerson - said on Sunday they would back his nomination.Meantime, the Justice Department said government anti-nepotism laws would not prevent Trump's son-in-law, Jared Kushner, from serving as a top adviser to the new president. Separately, a petition on Whitehouse.gov demanding that the billionaire president immediately release his tax returns passed 100 000 signatures, the threshold at which the White House is supposed to respond within 30 days.But Trump's advisers abruptly closed the door on that possibility - despite his repeated campaign promises to release the returns once a federal tax audit was completed."He's not going to release his tax returns," Conway said flatly on ABC. "We litigated this all through the election. People didn't care, they voted for him."Also on Sunday, at a swearing-in ceremony for several administration appointees, Trump held up a "beautiful letter" that he said Barack Obama had left for him."I just went to the Oval Office and found this beautiful letter from President Obama," he said."It was really very nice of him to do that and we will cherish that," he said, showing the room a white envelope before tucking it back in his jacket pocket.