A range of politicians, from civil rights legend John Lewis to President Obama to Rep. Eric Cantor (R-Va.), have publicly said Congress should pass some new version or revision to the Voting Rights Act after the Supreme Court gutted the law’s pre-clearance provision last week.

But that is a difficult task, even if some figures in both parties agree it’s a good idea.

Here are the three challenges to such an approach:

1. Coming up with a new formula

At it’s core, the Section 4 of the Voting Rights Act had essentially created and codified a group of states who received special scrutiny in regards to their voting laws. Nine entire states, most in the Deep South, were covered, along with six other counties. This was not a list any state wanted to be on, as it hearkened back to those states’ past histories of racial discrimination. It was akin to a “most racist states” list.

So politically, it will be extremely hard to create a new version of this list, even as research suggests many of the state’s covered under the original Section 4 of the Voting Rights Act are likely to remain problematic places with continuing conflict about race and voting. One option, advocated by Richard Pildes, an professor of law at NYU, is not to focus on states, but instead create some kind of broader, national voter protection provision that would simplify voter registration, improve the process so it does not involve hours of waiting in line and make it easy for people in states across the country, not just those in Section 4 states, to file suit against laws that complicate voting.

“The most effective means of protecting the rights of all voters should not be limited to the search for barriers that courts are likely to find racially discriminatory,” he wrote in a recent New York Times piece. “Instead, the more effective approach is to think in terms of solutions, federal or state, that eliminate unnecessary barriers and protect the right to vote in general, uniform terms.”

President Obama seemed to hint at going at this direction in a press conference after the Court’s VRA ruling was announced.

“The good news is that there are other potential remedies, and the most important one is to simply make sure that everybody around the country can vote and that everywhere around the country we’re not seeing seven-hour lines — we’re not seeing mechanisms put in place to make it harder for people to vote, but rather we should have mechanisms that make it easier to vote,” he said. “And that is within Congress’s power. Congress doesn’t have to target or identify a particular jurisdiction.  What it can do now is to say, regardless of where you are — regardless of where you live — there are going to be certain rules that apply to elections.”

But no one is quite sure what this kind of legislation would look like and how effective it would be in stopping unfair voting practices.

2. Getting it through the Senate

Senate Majority Leader Harry Reid (D-Nev.) has said revising the Voting Rights Act is a priority for him, and outgoing Sen. Mo Cowan, the chamber’s only African-American Democrat, said in an interview with MSNBC’s Up with Steve Kornacki that, “we’re not going to sit idly by on this.”

Democrats control 54 seats in the Senate, and it’s easy to imagine them finding a half dozen moderate Republicans to pass some kind of modest new voting law that does not single out individual Southern states.

That said, it’s not clear if the Senate will consider the VRA one of its biggest legislative priorities, with immigration reform still unfinished (it is likely the House will pass a different version of legislation on that issue and the two chambers will then debate it) and a host of fiscal issues to resolve by the end of the year. And it will be hard to pass anything in 2014, on the eve of the midterm elections.

In addition, there’s not an obvious champion for the VRA in the Senate. When Cowan leaves, the only black senator remaining will be Tim Scott of South Carolina, who applauded the Supreme Court’s decision last week and is unlikely to lead the creation of some kind of new voter protection law. A bloc of white Democratic senators could move a bill, but it’s no accident that one of the leading Hispanic Republicans (Marco Rubio) was one of the chief authors of the immigration bill. Personal identity still matters in politics.

3. Getting it through the House

Cantor aside, few House Republicans have expressed enthusiasm about revising or updating the Voting Rights Act. The House Republicans are as a bloc skeptical of broad federal laws, making them unlikely to support some kind of voting provision that would make it easy to strike down voter ID laws or force states to follow federal rules for voting.

The obvious pathway is for Democrats to push a bill through the Senate and then create public pressure on Speaker John A. Boehner (R-Ohio.) to hold a vote on a new VRA and allow it to pass with mostly Democratic votes. That, of course, is also the Democrats’ strategy for passing immigration reform.

Democrats argue that Republicans can’t be the party against the Voting Rights Act and immigration reform and expect to do better with minority voters in 2016. But that’s not likely to change the behavior of House Republicans, who are more focused on their elections in 2014. Most House Republicans live in relatively white districts where courting minority voters is not necessary to win.

Follow Perry Bacon Jr. on Twitter at @perrybaconjr