BOSTON -- Mitt Romney and Shannon O'Brien tried to convince voters Monday they each have the best plan to improve the economy.

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"Mitt Romney fashions himself as a national and international sales person knocking on the doors of Fortune 500 companies. When you understand that we are going to have to give away the store -- hundreds of millions of dollars in tax breaks to lure those bug companies to come here -- you realize that it is a formula that won't work," O'Brien said.

"Shannon O'Brien would be well-served to talk about her plan, and let me talk about my plan. My plan is designed to help all employers in Massachusetts, to bring jobs here, to make small employers more successful,"

NewsCenter 5's Janet Wu said that both candidates are prepping and positioning themselves for their second debate scheduled for Tuesday.

"The last debate felt like I was calling in my coordinates for incoming shells. I am hoping, that instead, we can talk about my visions for the future," Romney said.

O'Brien's advisers have told her to slow down her speaking -- hinting there may be fewer attacks.

"They're telling me to stick to the issues. They are telling me to be myself and to remind people why I am in public service," O'Brien said.

As for third party candidates trying to join the debate, Romney and O'Brien could not be further apart.

"The facilities that are sponsoring the debate -- they have set the rules. I would be very happy if Mitt Romney would agree to additional debates to have all the candidates attend," O'Brien said.

"I think it's a good idea to have the representatives of the smaller parties also included in the debates. I support them being included in those debates. I'm not going to do more debates myself," Romney said.

On the heels of the latest statewide poll showing O'Brien slightly ahead, both candidates must walk a fine line Tuesday, Wu said.

O'Brien wants to look like the frontrunner, but unlike the primary race she can't afford the luxury of staying above the fray.

Romney wants to maintain his cool, calm demeanor. But to push the momentum back in his direction, he may have to attack, and he won't have his surrogates on stage to help him out.