Trump tweets he's 'very concerned' Russia will help Democrats in midterms but offers no evidence

Under pressure to show he's taking the threat ofRussian interference seriously, U.S. President Donald Trump claimedwithout evidence Tuesday that Moscow will be "fighting very hard"to help Democrats win in the 2018 midterm elections.

Trump, who has offered mixed messages on Russian interference inU.S. electionsat times even calling it a "hoax"acknowledgedin a tweet that the midterms are a likely target.

He did not explain his reasoning beyond the tweet.

The U.S. intelligence community concluded Russia meddled in the 2016 election to try to help Trump win, and Russian President Vladimir Putin said last week at his joint press conference with Trump that he was rooting for the Republican.

On Tuesday, House Republicans held a hearing on election security in which lawmakers even some of Trump's closest GOP allies strongly criticized Russian interference and pointed to an indictment this month of 12 Russian intelligence officers. The indictment alleges that the Russians broke into Democratic email accounts and tried to penetrate state election systems.

During the hearing, ChristopherKrebsof the Department of Homeland Security said U.S. intelligence agencies haveobserved "continued malign influence operations" into 2018, though they do not appear to be "an effort at the same scope or scale" as in 2016.

Republican CongresswomanVirginia Foxx of North Carolina criticized Trump directly.

"Unfortunately, the president's recent comments at the U.S.-Russia summit in Helsinki failed to hold Putin accountable for his attacks on our country's interests and deter him from future indiscretions," she said.

Other Republicans were more careful not to directly disagree with the president.

"I don't think anyone here denies the fact that Russia attempted to meddle in the elections," said Congresswoman Jody Hiceof Georgia. "The issue of meddling is one thing, the issue of the president colluding is another and that is indeed a witch hunt."

Democrats said Republicans haven't done enough to keep the vote secure this fall. They asked for more questioning, more documents and more money for states to secure their election infrastructure.

"We need all of our Republican colleagues to conduct oversight not just use strong words," said Maryland Rep. Elijah Cummings, the top Democrat on the House oversight panel.

Earlier this year, Congress allocated $380 million to assist states with election security upgrades, and most of that money has been disbursed. Democrats want to continue the money through 2019, but Republicans have said new spending isn't needed.

The very makeup of the election infrastructure decentralized and different in every state provides some protection against hacking efforts. But state and local election officials have been working with the Department of Homeland Security to shore up their efforts after at least 21 state systems were scanned for vulnerabilities by Russian hackers and at least one state saw its voter registration system breached.