First it was going to be July, right after the Senate did its part. Next it was going to be September, once lawmakers had a chance to gauge constituent opinion. And then it was supposed to be this coming month of October, filling a window between two fiscal fights.

For those who have been predicting when the House would start debating immigration legislation, wrong and wrong are about to be met by wrong again. The current spending-and-borrowing morass now seems certain to consume the south side of the Capitol all October, and probably November and December as well.  

Congress has been a legislative serial monogamist — unable to even look at one front-page-worthy bill while another is being deliberated — which means that some of the most consequential changes to domestic policy in the past decade will probably have to wait until next year before being advanced or discarded outright.

So you might as well set March 3 as the no-longer-movable deadline for the House to pass some sort of immigration legislation or else declare the issue dead for the 113th Congress.

Why then? Because that’s the date of the first congressional primary of 2014 — in Texas, of all places, the state that shares the longest border with Mexico (1,954 miles) and vies with California for having illegal immigrants as the highest share of the population (just less than 7 percent).

If House members haven’t been asked to go on record before the midterm elections’ opening bell, the odds increase that the Republican majority leadership will never schedule any sort of immigration vote.

Explaining why this is so, and sketching the current state of play in the debate, requires a little review now that the issue’s been moribund for a couple of months.

Only a few dozen GOP members are anticipating genuinely close re-elections next fall. But many more represent such solidly Republican districts that their only electoral fear is a primary challenge from the right. (Two-thirds hold seats where their party has at least an 8-point advantage in the base vote.) At the same time, only one-third have constituencies that are even 10 percent Hispanic.

Those numbers help explain why so many in the House GOP rank and file would just as soon stay quiet, hoping talk of an overhaul fades into irreversible oblivion. They care plenty about raising the ire of tea party agitators back home, who blanch at all talk of allowing the undocumented to become citizens and don’t really want to spend another $30 billion trying to make the border less porous.

Such parochial anxieties far outweigh the interest many Republicans have in helping the business community keen to welcome more low-skilled and highly educated workers. Nor are they inclined to do their part to help their party’s standing with the electorate’s fastest-growing sector, which voted just 27 percent Republican last fall.

Those corporate and national political imperatives are why Speaker John A. Boehner, Majority Leader Eric Cantor and Judiciary Chairman Robert W. Goodlatte are all trying to keep alive the immigration overhaul drive. Their strategy, in place since the spring, is to build a critical mass of House GOP support one narrow bill at a time.

The five measures now ready for the floor would bolster border security, state and local immigration enforcement, employment verification, long-term visas for engineers and scientists, and seasonal visas for agricultural laborers. Also being drafted by GOP leaders are measures to create a guest-worker program and to legalize “DREAMers,” people brought into the United States illegally at a young age but on the right side of the law ever since.

But allowing all 11 million undocumented immigrants to pay fines, prove English proficiency and hold steady employment while waiting 10 years for a green card and three years more before becoming naturalized? Nothing’s in the offing, and the chance for a bipartisan path-to-citizenship breakthrough declined two weeks ago, when the one-time “gang of eight” House members negotiating for such a deal shrunk from seven to five with the departure of the second and third Republicans, Texans Sam Johnson and John Carter.

Boehner remains committed to a majority-of-the-majority threshold for any immigration bill getting a House vote, and overhaul advocates believe no more than 10 percent of Republicans would vote for the sort of citizenship path in the Senate bill (which got the votes of only 30 percent of GOP senators).

The best bank-shot outcome at the moment is that a sizable number of House Republicans are persuaded to vote for eventual citizenship for the 1.5 million “DREAMers.” Such a bill would at least make broadening the path to citizenship an appropriate topic in a conference committee, where negotiators might find a way around the complaint that the Senate bill creates a “special path” rewarding law-breakers. (The Obama administration opposes anything other than a clear path to citizenship for all illegals.)

Another outside-the-box option emerged last week from Minority Leader Nancy Pelosi, who started floating plans for a bill that might pass with support from perhaps 25 Republicans and all but a handful of Democrats. It would combine the original Senate “gang of eight” package (an easier path to citizenship than what passed) with the House’s border control approach (not as expensive as the Senate bill). If the trial balloon stays aloft, there’s an outside chance of an announcement Saturday, when immigration rallies are planned in 90 cities nationwide.

Those scenarios are decided long shots that would be realized only with some big leaps of political faith — starting with Boehner, who would have to put his speakership on the line to advance either one. But in the absence of legislative action for the next couple of months, wishful thinking is all proponents have left.