On a conference call with reporters today, GOP Rep. David Valadao of California, one of three House Republicans who has embraced the House Dem comprehensive immigration reform plan, announced that he is circulating a letter calling on the House GOP leadership to hold a vote on reform this year. He is asking fellow Republicans to sign on.

“I’m hoping to get a decent number,” Valadao said.

This will be interesting to watch, because it could shed light on a key question about the immigration debate: How many Republicans inside the House GOP caucus are genuinely willing to push the House GOP leadership to allow votes on reform?

Valadao and two other House Republicans — Jeff Denham and Ileana Ros-Lehtinen  — have already signed on with the House Dem plan, i.e., the Senate bill with a different border security measure attached. In a reference to the Dem plan, Valadao said: “More members are talking about signing on as well.”

The letter Valadao is circulating does not call on the House Gop leadership to hold a vote specifically on the House Dem plan. Rather, it calls for a vote on reform generally before the end of the year. Remember, if House Republicans vote on piecemeal measures, that could be a way to get to reform. If they vote on border security plus the Kids Act (which a majority of Republicans might support), or border security plus a legalization plan Republicans are said to be working on (a tougher lift), that could conceivably get us to conference.

GOP leaders may not hold a vote on anything this year, of course. But as Jonathan Bernstein details, if there is going to be a vote, it will be because enough mainstream Republicans want a vote. This new letter gives Republicans who say they want action on reform a way to publicly call on the leadership to allow a vote on it. Dem Rep. Luis Gutierrez regularly says there are 40 to 50 Republicans who want to vote for immigration reform. If this letter gets more than two dozen signatures and as many as three or four dozen — a very big “if” — that could be significant.

It’s become conventional wisdom that immigration reform must be dead because House Republicans don’t need to pass anything before the 2014 elections, which make acting even harder. It’s true that very few House Republicans are in districts with enough Latinos to impact the electoral outcome. But as Francis Wilkinson details, the history of previous reform votes suggests election years don’t have to be prohibitive. What’s more:

The blunt logic encouraging Republican support for immigration reform is unchanged; only the timing is in doubt. In 2014 or 2015 or 2016 Republicans will have to pass legislation. Because a party that gets 20 percent of the nonwhite vote, as the Republican presidential ticket did in 2012, is a party set to collide violently with the 21st century. And while Republican nativists appear eager to go down with the ship, others have been eyeing the approaching iceberg with more trepidation. The question is when, exactly, they will start scrambling for the lifeboats.

There are some House Republicans who do want immigration reform before the 2014 elections, and there are other House Republicans who want to vote on the issue because they recognize that the status quo is unacceptable and that the problem isn’t going away. How many are in those two categories? We need to find out.