President Obama has a long agenda for his State of the Union address, but it is important that he not forget the most fundamental democratic reform of all: repairing a broken election system that caused hundreds of thousands of people to stand in line for hours to vote last year. It is time to make good on his election-night promise.

Those seeking political power by making voting more inconvenient will resist reforms, but a better system would actually be good for both parties and, more important, the country.

Long lines are not the inevitable result of big turnouts in elections. They are the result of neglect, often deliberate, of an antiquated patchwork of registration systems that make it far too hard to get on the rolls. They are the result of states that won’t spend enough money for an adequate supply of voting machines, particularly in crowded cities and minority precincts. And they are the result of refusals to expand early voting programs, one of the best and easiest ways to increase participation.

The disparate effects of these policies were clear last fall. Blacks and Hispanics waited nearly twice as long to vote as whites, according to a study conducted at the Massachusetts Institute of Technology. Lines were longer in cities than in rural and suburban areas and tended to be longer in the South than in the North. The longest lines were in Florida, where Republicans strategically cut back on early voting in hopes of reducing the Democratic turnout. More than 200,000 people in the state were forced to give up without voting.

States generally play the principal role in setting election standards, but the Constitution explicitly gives Congress the right to step in at any time and remake the rules for electing its members. Given the generally mediocre job the states have done in modernizing their voting systems, Mr. Obama should demand federal legislation that makes it easier to register and get access to a ballot.

Modernizing the registration system is the most crucial step. Most states still use an antique paper method to register voters that doesn’t keep up with population change and keeps millions from voting. Congress needs to mandate (and help pay for) a computerized system that registers people whenever they interact with government agencies, and follows them from state to state. The Brennan Center for Justice estimates this would add 50 million people to the rolls permanently and save money through greater efficiency and accuracy.

Congress should also require a minimum early voting period for all states of at least 10 days and two weekends, and it should set basic standards for the number of polling places and voting machines or scanners that are needed for every thousand residents. Democrats have introduced bills in Congress to make these changes and more; Mr. Obama’s support would give them a boost, just as his support helps on gun control and immigration reforms.

Republicans have yet to sign on. Some are making the false claims that these bills would violate state rights or force people to register or vote. Others make the particularly appalling argument that tough registration systems do society a favor by filtering out unmotivated voters.

These are masks for their fear that a more expansive system will bring more Democratic voters to the polls. In fact, a modernized system would help to eliminate the concern about voter fraud that Republicans constantly espouse and would be good for everyone.