Georgia’s dominant GOP will enter Tuesday’s election with its sights set on winning a two-thirds “supermajority” in the Legislature, a majority so large Democrats would be unable to block proposed changes to the state constitution.

The effort, however, faces uncertain outcomes in several key races. Among them, DeKalb County incumbent Rep. Scott Holcomb, D-Atlanta, faces a pitched battle to retain his seat in one of this year’s nastiest political battles.

Across town, Republican newcomer Hunter Hill faces off in a tight race against longtime Senate Democrat Doug Stoner for Senate District 6, a district redrawn last year to include Atlanta’s GOP-leaning Buckhead.

GOP supermajorities in both the House and Senate could have a profound effect on legislation in Georgia.

Constitutional amendments need two-thirds support in both chambers to get on the ballot. If Republicans no longer need the support of the minority, they could be freer to pursue everything from stronger limits on spending, taxes and abortion to the creation of private school vouchers, all issues that have been raised in recent years.

Even the effort to re-create Milton County out of what is now north Fulton County would get a boost, said University of Georgia professor Charles Bullock, an authority on state politics.

Bullock said this election may be one of the GOP’s biggest opportunities to reach its goal. The state has begun experiencing demographic shifts — an increase in African-American, Latino and Asian voters in some areas — that seem more likely to help Democrats in the future.

“Whatever comes out of this election, we’re pretty close to the high-water mark for Republicans in this state,” Bullock said.

Republicans hold 115 of 180 House seats and need five more to meet the two-thirds threshold. In the Senate, Republicans hold 36 of 56 seats and need to pick up two to gain a two-thirds majority. On Election Day, 14 Senate seats and 43 House seats are up for grabs in contested races, although observers consider only a handful of those races close.

Rep. Allen Peake, R-Macon, secretary/treasurer of the House Republican Caucus, said he believes the GOP has a solid chance to reach its goal.

Peake would not identify all the races they’ve targeted but said there are “a couple of Democrats that are vulnerable, really vulnerable.”

“We have zeroed in on several we think can be beaten,” he said, “and we have devoted significant resources to winning those seats.”

One contest Peake confirmed as targeted is the challenge for House District 81, which was redrawn to make it more Republican.

Holcomb, the Democratic incumbent, faces attorney Chris Boedeker, who, in a campaign video that has since been deleted, accused Holcomb of using illegal drugs while serving as an Army officer. Holcomb served 12 years in the military and made three overseas deployments. The same video says Holcomb “brags” about his Army service.

The dust-up prompted at least two Republicans to endorse Holcomb, including Erick Erickson, the CNN contributor and editor of Redstate.com. Additionally, Boedeker’s challenger in the July Republican primary, Carla Roberts, said last week that while she’s not endorsing Holcomb, she can’t support Boedeker.

Boedeker declined to comment on GOP endorsements of his opponent. He realizes his campaign is one House Republicans might be counting on.

“It’s kind of in the back of everyone’s mind,” he said. “It’s not that (House Speaker Pro Tem) Jan Jones or anyone has said we’re trying to get to a supermajority, but the numbers don’t lie.”

Boedeker has also accused Holcomb of accepting campaign contributions from a brokerage charged with defrauding investors of $2.7 million. Holcomb is general counsel at JP Turner & Co., which was charged by the Securities and Exchange Commission in September.

But Holcomb said Boedeker has falsely named several employees of the brokerage as having a role in the case, which was settled. “No one from the company who donated to my campaign has been found liable of anything,” Holcomb said.

House Minority Leader Stacey Abrams, D-Atlanta, said Democrats want especially to protect incumbents in four seats, including the districts of Holcomb; Rep. Barbara Massey Reece, D-Menlo; Rep. Carl Epps, D-LaGrange; and Rep. Pedro Marin, D-Duluth.

The Senate race between Stoner, D-Smyrna, and Hill has been much less controversial. Stoner, a moderate first elected in 2002, has been endorsed by prominent members of the Atlanta business community. Hill, a West Point graduate, has highlighted his three tours of duty in Iraq and Afghanistan.