Sen. Tom Harkin (D-Iowa) may have finally won the right to vote next week on his signature issue — Labor Department attempts to redefine who can receive overtime pay — but this week he is scrambling to make sure that lawmakers who supported his bid to prevent that redefinition from taking effect do not change their votes.

Democrats are still reeling from last week’s announcement that the Labor Department had substantially rewritten its proposed overtime rules and eliminated many of the provisions that Harkin and his backers had contended would leave as many as 8 million Americans without overtime pay.

So, in a conference call today with a liberal think tank, Harkin plans to try to frame the debate with a preliminary analysis of the new regulations, which he said went “from profoundly terrible to just terrible.”

“Overall, it makes it easier for employers to not pay overtime, and it makes it harder for employees to claim their rights,” Harkin said in an interview Tuesday.

Still, Harkin is in a difficult position, and he acknowledges that the Labor Department took out the most egregious of its proposed rules, including a provision that would have specifically denied many military veterans overtime pay.

Senate Republicans conceded to his demand to vote on the amendment before the new rules were unveiled, after Harkin threatened to hold up every major piece of legislation moving through the chamber.

So now, the vote on his amendment to roll back the new rules could be scheduled for either Monday or Tuesday, and Harkin said he will be busy for the remainder of this week making sure that the 47 Democrats, six Republicans and one Independent who voted to block the rules last September don’t change their minds based on the Labor Department’s alterations.

Though the amendment was included in the Senate’s Labor, Health and Human Services, and Education spending bill last year, Republicans deleted it from the final conference report under pressure from the White House.

Several of Harkin’s GOP allies on the issue say they have not yet decided whether to support his attempt to block the revised rules.

“Basically, we’ve been talking with Alaskans to determine whether their concerns have been met” by the new rules, said Sen. Lisa Murkowski (R-Alaska).

Murkowski helped Harkin win a 54-45 vote last September on the overtime issue, but that vote was on proposed rules the Labor Department admitted could have caused more than 600,000 people to lose their overtime pay.

Now, the Labor Department contends that only 107,000 people making more than $100,000 a year would lose their overtime. Nearly 6.7 million workers would have their rights to overtime pay “strengthened,” according to a department release.

“We’re still in the process of reviewing,” said Murkowski.

That sentiment was echoed by other Harkin supporters, such as Sens. Lincoln Chafee (R-R.I.) and Olympia Snowe (R-Maine).

The Iowa Democrat is hoping to convince them to vote with him again using a preliminary analysis of what he says are problems with the new regulations.

For starters, Harkin said that the definition of “team leader” in the new regulations could allow employers to deny all manner of lower-level employees from overtime pay.

“There’s a huge loophole in this big enough to drive a railroad train through and all the trucks in America,” said Harkin.

From 1.5 million to 2.3 million people could lose their overtime pay under the team leader provision, alleged Harkin, referring to an independent analysis by a Massachusetts Institute of Technology management professor, Tom Kochan. Kochan provided the analysis at the urging of the Economic Policy Institute, a think tank associated with organized labor, said Ross Eisenbrey, EPI’s vice president and policy director.

According to a Labor Department talking points paper, the team-leader provision will “ensure overtime protection for ‘blue collar’ team leaders and are more protective of overtime pay for ‘white collar’ team leaders than the current regulations.”

Harkin also complained that the new rules appear to remove penalties for employers who improperly dock workers’ pay. Under current federal law, employers would have to do a two-year audit to determine who else they may have shortchanged if they are found to have docked a worker’s pay without cause.

The Labor Department’s rewrite would require companies to make sure the complaining employee gets back the docked pay without having to determine if other workers were treated improperly, said Harkin.

In addition, Harkin is not pleased with parts of the regulations that seem to target workers in certain industries. Under the rules, anyone who markets, promotes or services a product in the financial services industry could lose their overtime, unless they directly sell the financial product.

Similarly, “culinary arts” employees such as chefs and cooks could be exempt from overtime if they perform substantially similar work as executive chefs, who already do not receive overtime pay.

The Labor Department, however, denied that any industry was targeted by the rules.

“There are no blanket exemptions in the final rule for any occupations. In some cases the final rule merely adopts, word for word, the language from current Congressionally approved law, and in other cases merely adopts current federal case law. Either way, the status of these workers is unchanged from current law,” said Labor’s Wage and Hour Administrator Tammy McCutchen.

With all the back and forth, Harkin is still missing a critical piece in the rhetorical fight against the new regulations.

While the EPI is credited with determining that as many as 8 million Americans could have lost their overtime under Labor’s original proposed rules, Eisenbrey said the group had not yet come up with the number of people they believe could lose their overtime under the new rule and that the process could take months.

“My guess is that the number will be substantially less [than the original 8 million estimate], but there very well could be many, many people still affected,” Eisenbrey said.

“We’ll have some more analysis done before the regulations become final,” promised Harkin.