The authors of the House climate and energy bill will be courting undecideds over the next couple of weeks as they try to get their legislation passed by the House Energy and Environment Subcommittee.

Reps. Henry Waxman (D-Calif.) and Ed Markey (D-Mass.) want to make these potential swing voters happy while preserving the integrity of their bill. Meanwhile, industry is pushing the undecideds to help severely weaken or even kill the bill.

Of the 35 members of the House Energy and Environment Subcommittee, a dozen — 11 Democrats and one Republican — have expressed support for climate legislation, but have concerns about the Waxman-Markey bill in its current form. These swing votes are the prime targets of advertising campaigns by both industry groups and progressive organizations.

A complete version of the Waxman-Markey bill is expected over the next few days, with debate on amendments to begin sometime the week of May 4. After passing out of subcommittee, the bill will go on to the full Energy and Commerce Committee, where Democratic leaders hope to get it passed by Memorial Day.

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Here’s a rundown on the wild-card members of the subcommittee, what they’ve said about the bill, and how they want to change it.

Rick Boucher (D-Va.)

Boucher, a coal-state moderate who last year introduced his own draft climate bill with Rep. John Dingell (D-Mich.), has been leading the cadre of subcommittee members looking to make the bill more business-friendly. He and his allies have circulated a list of changes they’d like to see.

While the bill currently mandates a 20 percent reduction in greenhouse-gas emissions by 2020, Boucher is pushing to lower that goal to 6 percent.

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He wants to give out many emission permits free to energy-intensive industries and to the local distribution companies (LDCs) that funnel electricity to users, rather than auctioning the permits off, and he wants permit giveaways to the industrial sector to continue throughout the whole length of the cap-and-trade program, rather than be phased out. He wants to increase the amount of emissions reductions that can be met through offsets, and make the use of offsets more flexible. And he’s asking for the banking, borrowing, and strategic-reserve provisions — all mechanisms to help contain costs for businesses — to be made more flexible.

As a way to make the bill easier on the coal industry, Boucher is also pushing to ease performance standards for new coal-fired power plants, and grant “bonus allowances” to the first companies that install carbon-capture-and-sequestration technology.

“And at the end of the process, I hope I’ll be able to support the bill,” Boucher said last week. “In its current form, I cannot.”

Electric utilities have been the top campaign contributors to Boucher, giving him $753,960 over the past 20 years. He’s also received $264,106 from mining interests, $262,467 from oil and gas, and $203,696 from chemical and related manufacturing industries.

John Dingell (D-Mich.)

Dingell, who chaired the Energy and Commerce Committee before Waxman unseated him in a November coup, has also been a vocal critic of some of the bill’s provisions. His concerns largely mirror Boucher’s, though he’s been more public with his opinions.

“Nobody in this country realizes that cap-and-trade is a tax, and a great big one,” Dingell said during hearings on the bill last week, essentially repeating the Republican talking point that the bill amounts to a massive tax.

Also at the hearings, Dingell expressed concern about the “aggressive nature” of the bill’s renewable energy standard (RES). “I worry that 25 percent [renewable energy] in 15 years might be more than states can handle.” He has suggested allowing nuclear power to count toward a state’s baseline renewable levels.

In a nod to his home state’s major industry, Dingell has advocated for more funding within the bill for advanced automotive technologies. He’s also called for more funds for wildlife adaptation.

Dingell has received $1,183,547 over his career from electric utilities, making them his biggest contributor. He’s also received $953,465 from the automotive sector, and $409,091 from oil and gas interests.

G.K. Butterfield (D-N.C.)

Butterfield has questioned whether the bill has enough votes to make it out of committee — and his own vote is likely to be one of the deciding factors.

He’s particularly concerned about rising energy costs for average Americans and how that might affect the economy as a whole. He has called for 35 percent of revenue from the auctioning of pollution permits to go toward tax rebates to Americans in the lowest income brackets.

“For a low-income family, it’s absolutely impossible for them to absorb the costs,” Butterfield said last week.

He’s also criticized the RES in the bill: “We cannot achieve a 25 percent mandate by 2025. Not only is it impractical, but it is impossible.” He has suggested including nuclear, biomass, and efficiency in the options that states would have to meet their renewable-power requirements. He argues that Southern states, which are heavily coal-dependent and have been slower to adopt renewable power, will have particular trouble with an RES, so he’s requesting “special consideration for my state and several other states in the Southeast in our situation.” (Recent reports have found that the South has big potential for renewable-energy development and could in fact meet an ambitious RES.)

Electric utilities have been Butterfield’s fifth-largest donor, at $50,000 over his career so far.

Gene Green (D-Texas)

Green has requested that 5 percent of carbon allowances be given free of cost to the refinery industry, which is obviously large in his state.

“I can’t vote for a bill unless my refineries [are protected]; because of the nature of my district, it’s a job base and a tax base,” Green told Dow Jones. “Frankly, it’s a national-security issue. I don’t want to transfer production offshore for refined products, relying on imports from the Middle East and Venezuela.”

But Green is also worried about what would happen if regulation is left to the Environmental Protection Agency. “If Congress does not act, greenhouse gases could be regulated without the input of legislators who represent the diverse interests of this country,” he said.

The oil and gas sector is among Green’s biggest donors, at $330,613 over his career, as are electric utilities, at $271,800.

Mike Doyle (D-Pa.)

Doyle, who with Jay Inslee (D-Wash.) co-authored the portion of the Waxman-Markey bill that aims to help energy-intensive industries transition under carbon regulations, is another moderate leading negotiations with the bill’s authors.

As Pennsylvania is an industrial state, he’s concerned about the amount of pollution permits that will be given to industrial sectors like steel, aluminum, iron, paper, cement, glass, and chemicals and paper. He has also asked the bill’s authors to shave the RES from 25 percent renewables by 2025 down to 15 percent.

Doyle’s biggest donors have been industrial unions, which have contributed $359,450 to his campaigns. Electric utilities are also among his top donors, giving $257,427 over his career.

Charlie Gonzalez (D-Texas)

Gonzalez wants to make sure that the bill protects citizens from high energy costs. “It’s all about the consumer,” he told reporters last week. “Any increase in the price in energy looms large.”

Gonzalez is also worried about how the bill will impact oil refineries. His district houses the headquarters of Valero, one of the largest refiners in the country.

Industrial unions, the oil and gas sector, and electric utilities have all been among Gonzalez’s biggest contributors over the years.

Mary Bono Mack (R-Calif.)

Perhaps the lone swing Republican on the subcommittee, Bono Mack has said repeatedly that she is concerned about climate change, but also about the price tag of a climate bill. “I have big concerns about the costs and what it will do to our constituents,” she said during last week’s hearings.

But unlike the rest of her Republican colleagues, she’s said she is willing to work on a climate bill rather than try to torpedo it. As for whether she can support this bill in particular, she said, “Truly, I am in the undecided category … I’d love to see us do all we can on renewables. I’d love to see us move forward on energy independence.”

Other key swing votes on the panel include John Barrow (D-Ga.), Baron Hill (D-Ind.), Jim Matheson (D-Utah), Charlie Melancon (D-La.), and Mike Ross (D-Ark.).