One day after lawmakers approved Gov. Bill Haslam’s proposal to hike the gas tax to pay for transportation needs throughout Tennessee, Democrats in heavily Republican Williamson County were discussing an unusual idea: sending handwritten thank you notes to members of the local delegation who voted for the plan.

The idea, said Williamson County Democratic Party chairman Holly McCall, was to offer encouragement to Reps. Charles Sargent and Sam Whitson, two of the county’s Republicans who voted for the gas tax hike, known as the IMPROVE Act.

“I think it’s important. I do think we’ve gotten so hyper-partisan that it’s not enough to complain when people are doing the wrong thing," McCall said. "You have to tell them you appreciate when they’re doing the right thing."

After Wednesday’s vote, McCall’s praise of Republicans has hardly been isolated to Sargent and Whitson. She similarly heralded Haslam, who she called a moderate Republican who led the fight to provide necessary funding to help alleviate the transportation needs in a county that is one of the fastest growing in the state.

“I think Gov. Haslam is actually unusual these days because he is less defined by partisanship than a lot of elected officials on both sides of the aisle,” McCall said. “I do think he generally tries to do what is right and best for the citizens of Tennessee and not what is always expedient for his politics.”

Despite receiving support from Democrats like McCall and others, including the 23 members of the House minority party who helped pass the plan, Haslam’s proposal was a tough sell for some within his own party.

► Related: House, Senate approve Haslam's gas tax proposal

While the House debated the measure, Republicans like Rep. Andy Holt, R-Dresden, vehemently spoke against the proposal, calling it a betrayal to the party.

The state chapter of Americans for Prosperity, the conservative group that played a role in halting Haslam’s 2015 plan to expand health insurance to thousands of low-income Tennesseans, vowed to continue fighting.

“I think it is definitely going to have some repercussions in 2018, especially in the Middle Tennessee area, where the limited government Tea Party kind of ethos is much more popular among voters,” said Ben Cunningham, founder and president of the Nashville Tea Party, who has also worked for a group called Tennessee Tax Revolt.

Cunningham, who preferred an alternate funding plan proposed by Rep. David Hawk, R-Greeneville, over Haslam’s plan, said although the next election is not for another 15 months, it will be very easy to remind voters about the issue.

“We have got to make sure that our elected representatives pay a price, a very dear price, when they vote for tax increases,” he said.

No price to pay, Lamar Alexander says

But for all the talk from Holt and the more Tea Party-aligned Republicans in Tennessee, others, including U.S. Sen. Lamar Alexander and former Lt. Gov. Ron Ramsey, see the IMPROVE Act as a truly conservative approach to addressing an important issue.

“If you should never raise the gas tax to pay for roads are you supposed to borrow money? That doesn’t sound conservative to me," Alexander said in an interview. "Are you supposed to wait for Washington to send it to you and tell you what to do? That doesn’t sound conservative to me. The conservative thing to do is what Tennessee has done, which is to let the users pay the bill, to incur no debt and to pay as you go and not rely on Washington."

Ramsey agreed and dismissed the notion that Republicans who voted for the gas tax hike would be in trouble in 2018.

Ramsey said the counter argument is that those who voted against the IMPROVE Act voted against giving tax breaks to veterans, cuts to the sales tax on groceries and reductions on some business and investment taxes.

"For every mail piece that comes out that says you voted for a user fee to finance roads you could make five mail pieces on where they voted against tax cuts," Ramsey said.

Alexander said none of the Republicans who voted for gas tax increases while he was governor faced a backlash. "Not a single one of them got in trouble with the voters," said Alexander, who served as governor from 1979 to 1987.

"You hear this whole, it's a politically risky thing to vote for a gas tax...but we haven't really seen that," said Kevin Pula, a policy specialist with the National Conference of State Legislatures.

What are other states doing?

Since 2012, 90 percent of lawmakers across 10 states who voted in favor of increasing gas taxes and other fees to raise transportation revenue retained their seat, according to Transportation for America, a transit advocacy group.

During that time period as many as 25 states have approved plans to raise transportation revenues, with several others introducing legislation this year.

Pula said there are a variety of reasons so many are taking up the issue: states and the federal government, which had previously been reluctant to raise transportation taxes, declined to do so after the economic recession in the mid-2000s; the country's interstate system is hitting the end of its lifespan; and the federal funding states previously received has dwindled.

But Tennessee's action on Wednesday was unique among some other GOP-dominated Southern states.

Earlier this month, Alabama — which has a legislative makeup similar to Tennessee, with 98 Republicans out of 140 seats — rejected a plan that would have raised the gas tax to help pay for a $2.4 billion bond issue. In South Carolina, a gas tax proposal has failed to gain adequate support so far.

Part of Haslam's success could be due to his circumstances: he's a popular term-limited governor with a budget surplus.

"I've found and I think what he’s finding is you can be an even more effective governor in your second term than you can in your first time because you know what you’re doing, you know more about what you’re doing and people give you credit for not seeming political because you’re not running again," said Alexander, who praised Haslam for incorporating significant tax cuts, including to the state's tax on groceries, into his proposal.

Haslam's legacy with the plan

When Haslam introduced the legislation in January, he said he would’ve preferred to not take up the issue.

“I would have loved to have just cut taxes and be the governor that cut $540 million and started Tennessee Promise,” he said at the time. “But we have to do this as a state."

Although Haslam has been frequently known for his education initiatives — including a plan to provide free community college — many expect him to be remembered for what he's been able to accomplish with the IMPROVE Act, which is designed to help fund a $10 billion backlog in needed road and transportation projects.

"I think his major contribution as governor has been and will continue to be creating an opportunity for more students and adults to have at least two years of post-secondary education so they can get jobs," Alexander said. "But I think that continuing to have as a goal having the best four-lane highway system will rank right up at the top as a part of his legacy."

John Geer, a political science professor at Vanderbilt University, called the passage of the gas tax a real feather in Haslam's cap.

"Despite long odds, he managed to convince a reluctant legislature on the need for the gas tax. This bill will have important long term effects in advancing the state’s infrastructure, which will advance his legacy in significant ways," Geer said, while concurring that Haslam will largely be remembered as the "Education Governor."

And although Haslam has 20 months left in office, Alexander said the transportation funding issue is hardly over.

"When we passed our first program in 1981, I didn’t know that we would also have to pass one in 1985 and 1986 and 1989 in order to get the job done," Alexander said. "This isn’t the end of the story — the next governor and the next set of local officials may look at the road program and say in order to finish the job we need to do more."

Reach Joel Ebert at jebert@tennessean.com or 615-772-1681 and on Twitter @joelebert29.

This story originally appeared on The Tennessean’s website.