The U.S. Chamber of Commerce is taking a hard-line stance on tax reform, suggesting it will work to oust members of Congress who get in the way of rewriting and modernizing the U.S. tax code.

“We're going to hold them accountable about whether or not they help get tax reform across the finish line or whether or not they stood in the way,” said Neil Bradley, the Chamber's chief policy officer, in an interview Sunday on C-SPAN's “Newsmakers.”

Asked whether the Chamber would consider supporting primary challengers to sitting Republicans, Bradley said that “all options are on the table.”

President Trump and GOP leaders in Congress say they are committed to passing the most sweeping changes to the U.S. tax system since 1986, when President Ronald Reagan was in office, but a number of obstacles stand in the way to getting it done. There are major disagreements over how to pay for tax cuts so they don't add more to the debt.

The Chamber is a critical source of funding for many GOP candidates. It doled out more than $29 million in the 2016 election cycle and over $35 million in the 2014 midterms, according to the Center for Responsive Politics. The organization won't say how much is in its war chest for 2018, but it expects a similar range of spending.

The Chamber has typically used a scorecard to decide which candidates it will support. The scorecard is usually based on how politicians voted on the most important bills to the business community in the past year as well as over the course of their entire career. But in 2018 and 2020, “who helped versus who stood in the way of getting tax reform done” will be the determining factor in the Chamber's resource deployment, Bradley told The Washington Post.

Tom Donohue, the Chamber's CEO sent a letter to members of Congress and candidates in July that noted the Chamber endorsed 240 candidates in the election last year. “A year from now, we will be evaluating congressional candidates based on their support of the free enterprise system and their willingness to govern, as demonstrated by what role they played in helping enact the first major tax reform in 30 years,” he wrote.

Most of the money in 2016 went to help Republicans in key races in the general election. GOP Sens. Patrick J. Toomey of Pennsylvania, John McCain of Arizona and Todd C. Young of Indiana were major beneficiaries of Chamber cash last year. But five Democratic House members also received support, according to data compiled by the Center for Responsive Politics and the Chamber.

Trump is expected to push tax reform this week with events across the country. The Chamber is also launching a TV ad campaign in the coming days to rally support for tax reform in target districts by stressing how it will boost growth and create more jobs. Bradley wouldn't specify which districts the Chamber will start with, but he said it would be across “the entire spectrum” of GOP members and even some Democratic districts as well.

Decreasing the personal income, corporate and investment tax rates all enjoy broad support among Republicans and even some Democrats. But there's large disagreement, even among the GOP, about how to pay for tax cuts. Democrats and some more centrist Republicans are wary of cutting a lot of government funding for social programming. The other popular idea is to “close loopholes,” but that is easier said than done. Nearly every provision of the tax code has support from specific industries and their congressional allies.

Trump has proposed a rate as low as 15 percent for businesses, a major discount from the current top marginal rate of 39 percent.

“People would love a rate under 20 percent,” Bradley said. He wouldn't share exactly what the business community is willing to give up to get the rates down, but he did say as the rates go lower, it “matters a lot less” which tax breaks go away.

Wealthy conservative lobbying groups across the country are mounting a multimillion-dollar campaign to get voters excited about tax reform. The right-leaning American Action Network, for example, plans to spend up to $20 million on ads related to taxes this fall.

Emily Tisch Sussman, campaign director for the liberal Center for American Progress, thinks these latest moves by conservative groups are an indication of how dysfunctional the Republican Party has become under Trump. Despite controlling both the White House and Congress, they are struggling to get anything done.

“The Chamber is throwing its weight around to challenge congressional Republicans to act like it's regular times,” Sussman said. She predicts tax reform will be a hard sell to an American public that is weary that only the wealthy and big business will benefit. A Bloomberg poll in July found that only 4 percent of Americans believe taxes are the top issue for the country right now.

The Chamber's latest TV campaign is on top of the more than 100 events that Chambers of Commerce across the country have held thus far in August to rally support for tax reform from the grass roots. Treasury Secretary Steven Mnuchin and Senate Republican Leader Mitch McConnell spoke at a Chamber luncheon in Louisville last Monday. Their comments on tax reform were overshadowed by a post Mnuchin's wife made on social-media site Instagram that showed her in designer clothing disembarking from a government plane.

Early this year, Mnuchin predicted that tax reform would get done by August. That didn't happen, but Mnuchin said Friday, “I think we can get it done by the end of the year.”

Bradley is also optimistic. “I wouldn’t be surprised if we saw a fairly detailed proposal, perhaps end of September, beginning of October,” he said.