FBI Director James Comey is about to testify on the continuing U.S. investigation into Russia's meddling in last year's presidential election, but President Donald Trump on Monday accused Democrats of making up claims and pushed the agency and Congress to focus instead on media leaks.

The House Intelligence Committee will try to untangle a web of conspiracies – including Trump's unsupported allegation that his predecessor had Trump Tower "wiretapped" — Monday morning when it hears from Comey and Admiral Michael Rogers, director of the National Security Agency, in a rare open session.

"The Democrats made up and pushed the Russian story as an excuse for running a terrible campaign. Big advantage in Electoral College & lost!" Trump tweeted early Monday. "The real story that Congress, the FBI and others should be looking into is the leaking of Classified information. Must find leaker now!"

Here's what to watch for:

Was Trump wiretapped?

After Trump's Twitter posting March 4 claiming that former President Barack Obama "had my 'wires tapped' in Trump Tower just before the victory," Comey unsuccessfully urged the Justice Department to publicly deny the allegation, according to a U.S. official who requested anonymity in order to discuss sensitive issues.

Now, the hearing may give Comey and Rogers an opportunity to deny there was any such bugging. They're not likely to hear dissent from committee members on that score.

Representative Devin Nunes of California, the committee's Republican chairman, said on "Fox News Sunday" that "the president doesn't go and physically" wiretap someone. So if you take Trump literally, he said, "it didn't happen."

The panel's top Democrat, Representative Adam Schiff of California, said Sunday on NBC's "Meet the Press" that a classified dossier from the Justice Department delivered on Friday showed "no evidence to support the president's claim that he was wiretapped by his predecessor" so "I hope we can put an end to this wild goose chase, because what the president said was patently false."

Jeremy Bash, who was the CIA's chief of staff during the Obama administration, said Comey's testimony is likely to "complicate things" for Trump.

"He will either repudiate the wiretapping claim or he will leave open the idea that there is an investigation of the president's inner circle," Bash said. "Either story is bad for the president."

Was Trump's campaign under surveillance?

After the uproar that followed Trump's tweets on Obama and wiretapping, the president and his spokesmen recast the claim, saying he was referring to surveillance more broadly.

While many lawmakers from both parties have said there's no sign that Obama ordered spying on Trump, Nunes said Sunday he's pursuing whether there "were any other surveillance activities that were used" that led to the "unmasking of names and the leaking of names."

Nunes cited the case of Michael Flynn, Trump's first national security adviser. Flynn was forced to resign in February after it was revealed he'd spoken to Sergey Kislyak, Russia's ambassador to the U.S., during the presidential transition — and, crucially, misled Vice President Mike Pence about their discussions.

This month, Attorney General Jeff Sessions recused himself from probes related to Russia's role in the 2016 campaign and potential contacts between Russian officials and the Trump campaign team, after acknowledging that he met twice last year with Kislyak.

Intelligence agencies are known to listen in on communications by foreign leaders and diplomats, including ambassadors like Kislyak, but the contents of those calls aren't supposed to be disclosed.

Whatever happened to Russian hacking?

The ostensible topic of Monday's hearing is the Intelligence Committee's "Russian Active Measures Investigation" — in other words, the finding by U.S. intelligence agencies in January that Russia hacked into Democratic emails and leaked them to sow confusion in the U.S. electoral process, damage Democratic candidate Hillary Clinton, and help Trump's candidacy.

There was no finding, though, that hackers affected the actual vote-counting process. Russia has denied it engaged in hacking.

As intelligence agencies and congressional committees continue to investigate Russia's actions, lawmakers and intelligence experts have expressed concern that Moscow's model of interference — including selective leaking of information and attempts to control media narratives — could be replicated in other countries such as France, which holds its first round of presidential voting April 23.

Read how cyber-attackers may try to affect Europe's elections

Did Trump's aides collude with Russia?

Tying all of this together is the question of whether anyone close to Trump worked with the Russians during the campaign, whether in the hacking of Democrats or potential deal-making after the election.

Trump supporters including Flynn, former campaign chairman Paul Manafort, and energy consultant Carter Page have denied any improprieties in their contacts with Russian officials or intermediaries. Documents released last week by congressional Democrats show Flynn received more than $45,000 from RT, the Russian government-backed television network, for his participation at a December 2015 gala where he sat at President Vladimir Putin's table.

"Were there U.S. persons who were helping the Russians in any way?" Schiff asked Sunday. "Was there any form of collusion?"

Asked if there was evidence of collusion, Nunes responded, "I'll give you a very simple answer: No."

Can Comey satisfy lawmakers?

Comey, 56, angered Republicans in 2016 when he announced there weren't sufficient grounds to prosecute former Secretary of State Clinton or her aides for improper handling of classified information on her private email system.

Then, many Democrats were infuriated when Comey announced in late October that he was looking at some new evidence, believing he cost Clinton the election.

Comey is in his fourth year of a 10-year term heading the Federal Bureau of Investigation and can be removed only if he resigns or is fired by the president.

In an aside during a March 8 speech, the director indicated he has no intention of stepping down voluntarily. "You're stuck with me for about another six and a half years," he said.