With Sen. Kamala D. Harris joining the field of 2020 hopefuls, three out of three Democratic senators now running for president have pushed for major cyber policy reforms, from cracking down on election interference to stemming the flood of data breaches.

Harris (Calif.) was a co-sponsor of the most successful bipartisan election cybersecurity bill in the last Congress, while Sen. Kirsten Gillibrand (N.Y.) backed a separate bill that would have launched a 9/11 Commission-style investigation into Russian interference in the 2016 election. Sen. Elizabeth Warren (Mass.), meanwhile, introduced legislation in the wake of the massive Equifax data breach to ratchet up consequences for credit-rating agencies that fail to protect people's data.

All this sets the stage for cybersecurity - traditionally a fringe issue in presidential races - to be a big part of the national conversation during the 2020 contest. Democratic senators will almost certainly seek to turn cybersecurity into a wedge issue to attack President Trump, who has been hesitant to acknowledge Russia's culpability for a hacking and disinformation campaign meant to influence the 2016 election in his favor.

"RT if you agree: Americans deserve a transparent, independent investigation into Russia's involvement with the Trump camp," Harris tweeted in February 2017, in what could be a model for calling out the president on cyber issues.

This would mark a big change from pre-2016 election cycles, when the topic was barely discussed - and when a broader debate over cybersecurity policy was virtually unheard of. Even during the 2016 contest, the candidates mostly bickered about the security of former secretary of state Hillary Clinton's private email server and whether Trump would embrace intelligence agencies' conclusion that Russia was behind political hacks at the Democratic National Committee.

In this cycle, cybersecurity could be an important issue to the Democratic base: Democrats are more concerned about election security and more skeptical of the government's ability to manage a major cyberattack than are Republicans, according to recent public opinion polls. The 2020 candidates with lengthy cyber policy records could be judged on their accomplishments on this complex topic - and are likely to face tough questions about Russian hacking and disinformation operations, election security, and Chinese intellectual property theft.

Harris, who joined the Senate in 2017, has the most substantive cyber record among the candidates so far. As a member of the Senate's Homeland Security, Intelligence and Judiciary committees, she's been at the heart of cybersecurity policy action on the Hill.

She was one of five co-sponsors of the Secure Elections Act, the election security measure that came closest to becoming law last Congress, and helped deliver $380 million in election security money to states. She was also a co-sponsor of a separate bill from Sen. Ron Wyden (D-Ore.) that would require all elections to use paper ballots, a mandate favored by security experts.

She's also focused on Chinese cyberthreats, introducing legislation that would make it easier for U.S. companies to sue foreign actors, including China, for digital intellectual-property theft.

And Harris sponsored smaller bills that would create a cyber-workforce-exchange program between the Homeland Security Department and the private sector and upgrade cybersecurity at U.S. ports. As California's attorney general, she bolstered the state's ability to fight digital crimes, including identity theft.

Harris has been a frequent critic of Trump on cyber issues. Most recently, after the president claimed without evidence that China was interfering in the midterm elections, she penned a letter with other Democrats asking the director of national intelligence to either back up Trump's assertion or refute it.

Gillibrand's cyber focus has largely been on getting to the bottom of Russia's 2016 election interference. She co-sponsored a bill in 2017 with Sen. Lindsey O. Graham (R-S.C.) to launch a 9/11 Commission-style inquiry into Moscow's hacking and influence operations and make recommendations for future elections, though it did not pass.

She also sponsored a 2010 bill with then-Sen. John F. Kerry, who later served as secretary of state, to create a top cyber-diplomat post at the State Department, a move the agency made on its own a year later. The Trump administration eliminated that position.

Warren, a longtime critic of the financial sector who serves on the Senate Banking Committee, has focused most of her cyber work on holding companies in that sector accountable for data breaches. A bill she introduced with Sen. Mark R. Warner (D-Va.) in the wake of the Equifax incident would have imposed fines in the billions for similar breaches.

Gillibrand and Warner were also among 19 Senate Democrats who sent a letter urging the Trump administration to rethink its decision to eliminate the role of White House cybersecurity coordinator.

As the campaign heats up, expect these Democratic senators to take even more opportunities to position themselves against Trump and further outline their own policy positions.

They've already started laying the groundwork during their time in the Senate. Shortly after the president's July summit with Russian President Vladimir Putin in Helsinki, for example, Gillibrand tweeted: "@realDonaldTrump, instead of inviting Putin to the White House, how about you condemn him, and hold him accountable, for Russia's interference in the 2016 elections and their continuing efforts to undermine our democracy?"

joseph.marks@washpost.com