Gov. Jerry Brown is making a&nbsp;rare cameo at an Assembly Democratic caucus gathering on Wednesday, giving&nbsp;an in-person sales pitch for his $52-billion transportation plan. But he'll be facing a wary audience of fellow Democrats.Brown's visit comes one day after tensions flared at the caucus' regular Tuesday lunch, where fears about a tough political vote were compounded by complaints about the short turnaround between the deal's unveiling and Thursday's&nbsp;scheduled vote."Part of the frustration that you're hearing is that it's a self-imposed deadline," said Assemblywoman Anna Caballero (D-Salinas). "My perspective is that people want to be reflective about how we handle a big change, and so we want to make sure we're checking in with our constituents and this doesn't leave much time."The bill requires a two-thirds vote to pass. That would require every Democrat in the Senate and all but one Democrat in the Assembly to vote yes.The scramble for votes has exposed the fractures within the large Democratic caucus, but&nbsp;unlike in past legislative battles, the fault lines are regional rather than ideological.The informal but powerful group of business-friendly Democrats, who self-identify as moderates, are not voting as a bloc on the package. Some "mods,"&nbsp;including Assemblyman&nbsp;Jim Frazier of Oakley, who helped&nbsp;shepherd the proposal, are on board. Others, such as Assemblyman Rudy Salas&nbsp;of Bakersfield, are on the fence.Assemblyman Jim Cooper of Elk Grove, the other Mod Caucus co-chair, said he was undecided, despite appearing at a news conference at the plan's unveiling last week. He said he attended the media briefing to show general support for a transportation package, but he continued to have reservations about the current proposal."My constituents in my district are overwhelmingly against the tax," he said.He said resistance was coming for several&nbsp;reasons, not just from one centrist faction."If someone's saying this is a Mod Caucus play, they are dead wrong," Cooper said. "It's about their district."Salas struck a similar note."I'm approaching this as the representative from Bakersfield," he&nbsp;said. "I have to think of the fact that in my district, people have to drive a distance to drop their kids off to school. They have to drive a further distance even to go to work. And does this transportation plan take into account the distance that they travel in rural areas?"Business groups, such as the California Chamber of Commerce, which&nbsp;Salas is ordinarily&nbsp;aligned with, are in favor of the proposal. But agricultural interests, which&nbsp;flex muscle in the Central Valley, are opposed.Salas said he was taking the temperature from constituents not affiliated with interest groups at a local event last week."They were saying, 'Yeah,&nbsp;something needs to be on transportation, but this is too steep,'"&nbsp;he said.Another member who sometimes votes with the business-aligned caucus, Assemblyman Jose Medina, appeared at a rally in favor of the plan with the governor and legislative leaders in his Riverside district on Tuesday.Medina had a rosier outlook on prospects for the plan."I'm a teacher," he said.&nbsp;"I'm always optimistic."