Former Virginia governor Terry McAuliffe. (Timothy C. Wright/For the Washington Post)

Former Virginia governor Terry McAuliffe, a potential 2020 Democratic presidential candidate, says he plans to barnstorm 20 states this year to help Democrats win greater control of state legislative maps.

“The 2018 elections are going to determine who controls those maps in 2021,” McAuliffe said in an interview Thursday. “I would encourage every Democrat not to talk about 2020. Our future is on the line, literally.”

McAuliffe’s travel comes in his new role as the state engagement chair of the National Democratic Redistricting Committee, a group he helped found with former president Barack Obama, House Minority Leader Nancy Pelosi (D-Calif.) and former attorney general Eric H. Holder Jr.

The group’s mission, backed by a $30 million budget, is to eliminate Republican control of the redistricting process after the 2020 Census. McAuliffe plans to hold public events, help provide legal counsel and work with local officials in gubernatorial, state legislative and ballot campaigns.

“In his role with NDRC, he will be sharing his story with governors, local elected officials, and candidates across the country,” said Holder, the chairman of the NDRC, in a statement to the Post.

The NDRC announced a plan to target its efforts in 12 states last week, including nine gubernatorial races, 20 legislative chamber contests and several ballot measures in an effort to break Republican control of the process in several parts of the country. Eight other states, including New Hampshire, South Carolina and Maine, have been listed as watch list states.

Democratic officials in Ohio, one of the targeted states, hope to make redistricting an election year issue, starting with a ballot proposal that will be put to voters as part of the May 8 primary. Both Holder and McAuliffe are scheduled to do events there in the coming months, emphasizing the importance of electing Democrats statewide to influence redistricting.

“The gerrymandering issue is now on the ballot in multiple races come November, and it is on the ballot in May in a direct up or down vote,” said David Pepper, the state Democratic Party chairman. “The presence of Eric Holder and Terry McAuliffe and others nationally makes a huge difference.”

Currently, Republican officeholders completely control the redistricting process in 21 states, compared to five states where Democrats have control, either with veto proof majorities in the legislature or by controlling both the legislature and the governors mansion.

The advantage, which increased after the 2010 elections, has given the GOP the upper hand in the U.S. House, and in many state legislative bodies, where the margin of Republican control is far greater than the popular vote margin. In 2012, for instance, Democrats received 1.4 million more votes nationwide in U.S. House races, while winning 33 fewer congressional seats.

Legal challenges to the 2010 redistricting round are still pending in eight states, according to a tally kept by the Brennan Center for Justice, including multiple cases before the U.S. Supreme Court. The Pennsylvania Supreme Court recently ordered a redrawing of congressional district lines before the 2018 elections, after finding the current lines violated the state’s constitution.

As governor of Virginia, McAuliffe fought against a redistricting plan by his own Republican legislature, eventually winning a new map that gave Democrats a fourth congressional seat in the state. Republicans now hold seven of the 11 seats in Virginia, a state that voted for Democratic presidential candidate Hillary Clinton in 2016 and Democratic Gov. Ralph Northam in 2017.

“The action is happening in the states and we as Democrats had better get in the game,” McAuliffe said.

He began working on the effort through the Democratic Governors' Association in 2015. The idea for the NDRC was born on the sidelines of the 2016 Democratic National Convention in Philadelphia, and Obama signed on to help the effort before he left office.

Democrats have launched a second front in the redistricting effort in recent weeks by raising public alarm about a Trump administration proposal to add a citizenship question to the 2020 Census, a decision that demographers say will give an advantage to Republicans by lowering the response rate among Democratic-leaning immigrant communities.

McAuliffe said the issue was discussed at House caucus retreat last week, where he and Holder addressed Democrats.

“It is clear to us that they are going to try to undercount Democratic voters,” McAuliffe said of the Trump administration’s plans for the census. To fight back, he said, Democrats need to regain budgetary sway over the process by winning back control of the House this year.

“The ‘18 elections are very important,” McAuliffe said, who declined questions about his presidential ambitions. “2020 will come soon enough.”