With the deadline for acting on a transportation bill approaching at the end of this week, Democrats are ramping up the pressure on Republicans to take up the Senate-passed bill or something similar.

In some ways, it appears to be working. House Republicans continued to resist Democrats’ pressure, but for the second time in two days, GOP leaders had to delay a short-term extension of highway programs after House Democrats threatened to withhold their votes.

GOP leaders needed Democratic votes because they sought to pass the measure under suspension of the rules, a move that is typically reserved for noncontroversial measures and requires a two-thirds vote for passage.

On Monday, Speaker John Boehner (R-Ohio) was forced to scrap a plan to pass a 90-day extension after Democratic leaders began whipping against it.

On Tuesday, Boehner opted to bring a 60-day bill to the floor, a measure that Senate Democrats had been expected to take up if the House continued to refuse to move on the Senate’s two-year, $109 billion transportation bill.

But House Democrats, who have been closely coordinating with Senate Democrats, again came out blazing. “I reject the 60-day [extension] when we can do so much more,” House Minority Leader Nancy Pelosi (Calif.) said on the floor, demanding that Republicans bring the Senate’s version of the bill to the floor.

Boehner is in a difficult position. According to Republicans, he remains committed to passing a multiyear transportation bill that includes significant reforms to highway and transit programs, and he strongly opposes any discussion of passing the Senate measure, even though he previously indicated he would bring it up and pass it if House Republicans could not coalesce around a different version.

But how long he can hold out is unclear. Democrats have shown no willingness to negotiate with him, given the Senate bill’s strong bipartisan support. The measure passed the Senate earlier this month, 74-22.

And, an increasing number of House Republicans are beginning to say the House should take up the Senate bill, aides said.

Republican Reps. Robert Dold (Ill.), Judy Biggert (Ill.) and Charles Bass (N.H.) signed on to a letter Monday with Democrats calling for House leaders to take up the Senate transportation measure.

House Republicans leaders have struggled to pass a transportation bill this year and continue to discuss options within their caucus.

Initially they pushed for a $260 billion, five-year package funded by oil and gas drilling revenue. But they changed course after conservatives panned the proposal as too costly. They also explored passing an 18-month package and have yet to work out a path forward.

Before the House decision to pull the second bill, Senate Majority Leader Harry Reid (D-Nev.) would not commit to taking up a short-term measure from the House.

“My feelings haven’t changed,” Reid said. “I don’t like the extension.”

But it was expected that if the House were to clear the 60-day extension and send it to the Senate, Reid would have brought it up.

“We’ll do the extension, but it’s destructive,” Environment and Public Works Chairman Barbara Boxer (D-Calif.) said before the House decided to pull its bill.

Democrats wanted to reduce the extension from 90 days to 60 days or fewer because they want to prevent Republicans from having enough time to draft their own version, aides said.

The other reason, Boxer noted, is that states are delaying projects and construction programs, which is jeopardizing tens of thousands of jobs.

Boxer said she spoke with transportation officials in North Carolina and was told that 41,000 jobs are on the line.

“They are delaying the remainder of their 2012 projects totaling $1.2 billion … that would employ 41,000 people … because of the dithering of the House,” she said.

Boxer added that about 50,000 jobs in Boehner’s home state of Ohio and about 40,000 jobs in Virginia, the home state of House Majority Leader Eric Cantor (R), are on the line.

Boxer chalked up the House decision to hold off on short-term extensions to the pressure being exerted from House and Senate Democrats.

“I’m glad they are pulling this vote because they ought to instead pass the bipartisan Senate transportation bill,” she said on the Senate floor.

Reid said Senate Democrats are planning floor speeches in an effort to keep up the intensity.

“We are going to have [a] series of speeches in the next 48 hours talking about why the Republicans in the House … are telling their leaders to take up the Senate bill,” Reid said.

“It could pass over there so easy,” he added.

Sen. James Inhofe (R-Okla.), ranking member of the Environment and Public Works Committee, also said he wanted House Republicans to pass the Senate bill but expects that a short-term measure will be passed.

“I would have preferred not to do it with a short-term extension; extensions are not good,” Inhofe said. “But if they are unable to come up with something to get to conference, the answer is an extension.”

“I prefer the short extension, rather than the longer extension,” Inhofe continued. “Shorter is better because they never do anything until about three days before it expire[s] anyway.”