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WASHINGTON (AP) -- 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.

"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. On Sunday, Trump demanded 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 U.S. 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.

Separately, 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 Chairman 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., chairman 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."

Trump's request carries some risk, particularly if the committees unearth damaging information about him or his associates. Committee Democrats will have access to the information and could wield anything negative against the president. Asking Congress to conduct a much broader investigation than originally envisioned also ensures the Russia issue will hang over the White House for months.

Obama's director of national intelligence, James Clapper, said nothing matching Trump's claims had taken place.

"Absolutely, I can deny it," said Clapper, who left government when Trump took office. Other Obama representatives also denied Trump's allegation, which the FBI has asked the Justice Department to dispute, a U.S. official told The Associated Press on Sunday. The official wasn't authorized to discuss the request by name and spoke on condition of anonymity.

The department, however, has issued no such statement. DOJ spokeswoman Sarah Isgur Flores declined to comment Sunday, and an FBI spokesman also did not comment.

Josh Earnest, who was Obama's White House press secretary, said presidents do not have authority to unilaterally order the wiretapping of American citizens, as Trump has alleged was done to him. FBI investigators and Justice Department officials must seek approval from a federal judge for such a step. Earnest accused Trump of leveling the allegation to distract from the attention being given to the Russia issue.

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