US President-elect Donald Trump with Republican National Committee Chairman Reince Priebus and Vice President-elect Mike Pence at an election-night rally in New York City on November 9. REUTERS/Jonathan Ernst The Republican Party is thought to have been targeted by Russian hackers in ways similar to the hacks that nearly upended the Democratic Party — via malicious emails.

According to a report from The Wall Street Journal published Thursday night, US intelligence experts said the Russian hackers who tried to break into the Republican National Committee targeted the email address of a former employee.

The attempts apparently did not go very far, according to two cybersecurity officials briefed on the matter and cited by The Journal, who said a phishing campaign last spring that targeted the sole email address of that former employee essentially failed.

Messages sent to that address were quarantined by email filters traditionally designed to stop spam and potentially malicious emails, the experts said. GOP officials apparently had no idea hackers tried to breach their systems until June, after Democratic Party leaders announced that they were hacked, according to another unnamed source cited by The Journal.

The report said Republican leaders suspected they too may have been targeted and brought in a cybersecurity firm to investigate. The FBI later got involved, the newspaper said.

"The apparently successful blocking of a Russian espionage operation offers one possible explanation why the GOP's main political organization didn't suffer the same fate as its Democratic counterpart," The Journal's Devlin Barrett and Julian E. Barnes wrote.

Hillary Clinton conceded the presidential election at the New Yorker Hotel on November 9. Justin Sullivan / Getty

Last week, The Washington Post and The New York Times reported findings from the CIA that suggested the Republican Party had also been hacked, in a report that framed the much-larger Democratic Party breach as evidence that Russia tried to help Donald Trump win the election.

Some Republican leaders have painted the ordeal as partisan politics, but there is growing bipartisan support for a complete accounting of the matter. Sen. Lindsey Graham of South Carolina, a former Republican presidential candidate, said in a CNN interview on Wednesday that his campaign accounts were breached. Graham said he wanted "crippling sanctions" against Russia as punishment.

President Barack Obama echoed those sentiments in excerpts from an interview with NPR released Thursday:

"I think there is no doubt that when any foreign government tries to impact the integrity of our elections ... we need to take action and we will."