President Trump's senior advisors defended White House attacks on the news media&nbsp;and incorrect claims about the size of the crowd at his inauguration,&nbsp;accusing news organizations Sunday&nbsp;of trying to undermine Trump's legitimacy.The pushback came a day after White House Press Secretary&nbsp;Sean Spicer, standing for the first time behind the West Wing briefing room lectern, incorrectly said Trump's swearing-in ceremony drew "the largest audience to ever witness an inauguration." Spicer also contradicted his own claim of about a minute earlier that crowd totals were unavailable.&nbsp;Spicer's appearance set a combative tone for the first full day of the Trump presidency.Challenged on NBC's "Meet the Press" about Spicer making incorrect claims,&nbsp;Trump advisor Kellyanne Conway&nbsp;made a startling characterization, that Spicer gave "alternative facts."&ldquo;You're saying it's a falsehood, and Sean Spicer, our press secretary, gave alternative facts to that,&rdquo; Conway told host Chuck Todd, who immediately interjected his disbelief over her description.&nbsp;Conway eventually backed off Spicer's adamant claims and inflated crowd estimates. &ldquo;I don&rsquo;t think you can prove those numbers one way or the another,&rdquo; she said.&nbsp;&ldquo;There's no way to really quantify crowds."However, police and cities use statistical methods&nbsp;to estimate crowd sizes to protect public safety during large events. And scientists use available evidence to tally crowd sizes, as in this comparison of the inauguration crowd and Saturday's women's march in Washington.&nbsp;"There's an obsession by the media to delegitimize this president, and we are not going to sit around and let it happen," White House Chief of Staff Reince Priebus&nbsp;said on &ldquo;Fox News Sunday.&rdquo;"We're going to fight back tooth and nail every day, and twice on Sunday," Priebus said.Trump aides&nbsp;also slammed the news media&nbsp;for an incorrect&nbsp;report that a bust of Martin Luther King&nbsp;Jr. had been removed from the Oval Office. It was moved to a difference place in the room."You can't have false reports like that and expect us to, you know, not wonder why we're covered and treated so differently and unfairly," Conway said on CBS'&nbsp;"Face the Nation."The report, disseminated by a reporter in the Oval Office acting as a representative for the larger press corps,&nbsp;was corrected less than an hour later and the reporter apologized.