Updated: 4:14 p.m.

Speaker John Boehner today said he would prefer a six-month extension of the highway bill if the bicameral conference committee cannot come to a resolution by the end of the month.

“I’m very hopeful that they’ll get into serious discussions quickly because if we get up to June 30, I am not interested in some 30-day extension,” the Ohio Republican told reporters. “Frankly I think if we get to June 30, it’d be a six-month extension and move this thing out of the political realm that it appears to be in at this moment.”

A six-month extension would require Congress to deal with reauthorizing transportation programs during an expected post-election, lame-duck session — adding to an already long list of critical legislative priorities including extending Bush-era tax cuts, raising the debt limit and undoing the so-called sequester of automatic spending cuts set to begin in January.

Boehner’s comments underscore the reality facing House and Senate conferees; with the election looming and the legislative calendar extremely short, significant progress needs to be made in the next 24 hours if they expect to pass a full reauthorization this year.

Senate Environment and Public Works Chairman Barbara Boxer (D-Calif.) and ranking member James Inhofe (R-Okla.), who head the Senate conferees, delivered an offer to the House earlier this week. House Republicans are expected to propose a counteroffer today.

The Senate intends to respond to the offer promptly, and in an email blast shortly after Boehner’s comments, Boxer said she is disappointed.

“I am very disappointed that Speaker Boehner is even talking about a long-term transportation extension, which would lead to the Highway Trust Fund going bankrupt, when all of our efforts must be focused on passing a transportation bill by the June 30th deadline,” the California Democrat said in the statement. “Three million jobs and thousands of businesses are at stake.”

But House Transportation and Infrastructure Chairman John Mica said Boehner’s comments were merely meant to spur action and that the six-month extension is not set.

“He mentioned that, but I’ve talked to him about that before his comments and that’s not firmly fixed yet,” the Florida Republican said. “He just wanted to lay it on the line, that we needed to take this seriously and get it done. … The Speaker laid down a marker today and put everyone on notice. We have to act responsibly because you can’t close down all the transportation projects in the country, that’s too high a price to pay.”

Mica said the House offer will be split into thirds, with a transportation offer coming today and others coming Friday and Monday. He said he will hold a conference call on Wednesday or Thursday with his conferees.

Boehner said he would prefer to strike a bipartisan deal. But House Minority Leader Nancy Pelosi, speaking before Boehner, told reporters that she doubts the sincerity of House Republicans.

“I think the Republicans in the House want to do nothing more than keep having extensions. Maybe they’ll do something right before the election but it will be too late to help create jobs,” the California Democrat said. “If they do the extensions they’re using up the … highway trust fund, they’re hurting job creation — in fact people will lose jobs — and it’s just the wrong thing to do.”

She suggested that the House hold a straight up-or-down vote on the Senate-passed version of the highway bill, which passed that chamber with strong bipartisan support.

“I believe the bill would pass. So what are they afraid of? Are they afraid of passing a transportation bill that would … save more than 2 million jobs?” Pelosi asked. “If there is a sincere wish to create or save these 2 million jobs, if there’s a sincere wish to help lift up the construction industry … then the Republicans would bring it up.”

John Stanton contributed to this report.