Washington - White House officials on Monday defended President Donald Trump's explosive claim that Barack Obama tapped Trump's telephones during last year's election, although they won't say where that information came from and left open the possibility that it isn't true.In televised interviews, Kellyanne Conway and Sarah Huckabee Sanders said Trump firmly believes the allegations he made on Twitter over the weekend. The aides said any ambiguity surrounding the issue is all the more reason for Congress to investigate the matter.May have access"We'd like to know for sure," Sanders, deputy White House press secretary, told NBC's "Today" show.The House and Senate intelligence committees, and the FBI, are investigating contacts between Trump's campaign and Russian officials, as well as whether Moscow tried to influence the 2016 election. Trump demanded on Sunday that they broaden the scope of their inquiries to include Obama's potential abuse of his executive powers.When asked where Trump was getting his information from, Sanders said the president "may have access to documents that I don't know about."Likewise, Conway said that "credible news sources" suggested there was politically motivated activity during the campaign. But Conway also said Trump might have access to other information she and others don't."He is the president of the United States," Conway told Fox News' "Fox & Friends. "He has information and intelligence that the rest of us do not."Trump is said to be frustrated by his senior advisers' inability to tamp down allegations about contacts between his campaign aides and the Russian government. Compounding the situation was the revelation last week that former US senator and now Attorney General Jeff Sessions, an early Trump campaign supporter, had met twice with the Russian ambassador but didn't disclose that to lawmakers when he was asked about it during his Senate confirmation hearing.Compile our findingsSeparately, an Indiana newspaper reported that Vice President Mike Pence used personal email to conduct state business when he was governor of Indiana. The revelation recalled the use of personal email by Trump's 2016 opponent, Hillary Clinton, when she was secretary of state. The issue dogged Clinton for most of the presidential campaign.Senate Intelligence Committee Chair Richard Burr, R-N.C., said in a statement that the panel "will follow the evidence where it leads and we will continue to be guided by the intelligence and facts as we compile our findings."Rep Devin Nunes, R-Calif., chair of the House Intelligence Committee, said in a statement that the committee "will make inquiries into whether the government was conducting surveillance activities on any political party's campaign officials or surrogates."