The rapidly filling Republican field of presidential candidates is about to get even more crowded, as two more GOP hopefuls plan to enter the fray.

Rick Perry, the three-term governor of Texas, and Lindsey Graham, the senior senator from South Carolina, will join half-a-dozen already declared candidates for president, including two Democratic hopefuls.

Graham is expected to announce his bid June 1, while Perry could announce his campaign on June 4.

The two candidates bring years of governing experience to the table, but of vastly different quality. The anti-regulation and anti-tax message of Perry is likely to appeal to many business owners, while others are likely to find Graham's centrism a breath of fresh air after decades of hyper-partisan fighting in Washington.

Graham has served as senator since 2003, when he replaced Strom Thurmond, the longest-serving senator in U.S history who died that year. He has a reputation for crossing the political aisle to work with Democrats on key legislation. In 2010, for example, he worked with Senators John Kerry and Joseph Lieberman on a climate change bill that would have reined in carbon emissions by businesses. Graham ultimately backed away from the legislation, which was killed by Congress. 

"I think the Republican Party has to do some soul searching," Graham told the Council on Foreign Relations, a nonpartisan think tank, in March. "Before we can be bipartisan, we've got to figure out where we are as a party."

In recent years, Graham has said he'd renege on promises not to raise taxes if it meant getting rid of the national debt, but he'd do so by eliminating popular middle-class loopholes, such as the mortgage interest deduction.

Perry, who also ran for president in the 2012, making much of his five years in the U.S. Air Force, was first elected to the Texas House of Representatives as a Democrat 1984, but he switched party affiliations in 1990. His bid for the presidency was marred by a seemingly inadequate knowledge of national affairs, which was most pronounced during a televised debate that showed Perry unable to remember the name of a third federal department he'd said he planned to cut, along with the Departments of Commerce and Education. (It turned out to be the Department of Energy, he said later.)

"What we don't know about Perry is whether he has gone to school since then, and done his homework," says Elaine Kamarck, a senior fellow at the policy think tank Brookings Institute.

During his tenure as governor, Perry established the Texas Enterprise Fund, which created incentives to bring businesses to Texas. He also had a strong pro-infrastructure development bent, advocating for the Trans-Texas Corridor, a super-corridor that would have divided business and commuter traffic. Opponents saw the plan as a misuse of funds, and the project died in 2010.

Perry also had an uneven record on taxes, cutting them for property owners, but raising them for small business owners by broadening the state's franchise tax base. 

Additionally, Perry has supported immigration reform, only if it is coupled with beefed up border security. And in a turn that is likely to be most significant for his campaign, in 2014 he was indicted for corruption, on charges stemming from his veto of a $7.5 million appropriation for a public integrity unit, seen as a bid to pressure a district attorney to step down. That case is ongoing.

The slow and steady drumbeat of candidates has been rolling along this spring, and Graham and Perry join Ben Carson, Ted Cruz, Mike Huckabee, Marco Rubio, Rand Paul, and Carly Fiorina, the former head of Hewlett-Packard, who announced her presidential bid just a few weeks ago. Former Secretary of State Hillary Clinton and Vermont Senator Bernie Sanders announced their intentions to run in April. All told, about 16 Republican candidates are expected to join the race, including Wisconsin Governor Scott Walker, and Jeb Bush, the former governor or Florida, who have yet to declare their plans to run.

So far, though, the campaign has offered precious little to small business owners.

Last week, Clinton, in a post on Linkedin, spelled out how her presidency would serve small business owners. Among her plans, she said she would increase access to capital, simplifying the tax code, and expanding access to new markets.

Similarly, Carly Fiorina, who has worked with the Milstein Symposium to study how to re-engage entrepreneurship in the U.S., told Inc. in a recent interview that she supports impact investing from large foundations to troubled areas.

"We have a situation now where small businesses are suffering, and we have fewer starting and more failing than 40 years ago," Fiorina said. "If we can't get this engine to go again, our economy won't produce at its capacity, and the middle class will continue to be squeezed."

In a match-up poll between Clinton and Republican candidates, Clinton has a substantial lead against Rubio and Cruz, while Walker beats Clinton by four points, according to a late April poll by the Nelson A. Rockefeller Center at Dartmouth College.

"There hasn't been such a wide open field since Goldwater ran against Rockefeller," Bill Whalen, a research fellow specializing in California and national politics at the Hoover Institution, said in earlier interview with Inc. "Even then it was a fairly focused race, now there is not one solid frontrunner."