John McCain fired some heavy shots at Mitt Romney and his other opponnents for the Republican nomination on Fox News Sunday, telling host Chris Wallace that his record as a fiscal conservative in Congress and his military background solidify his position as a "real" conservative Republican.

McCain slammed Romney for claiming to be "the real Republican" in the race while having a record of taking liberal positions on many issues--including criticizing Ronald Reagan, contributing to a Democratic candidate running in New Hampshire and supporting Paul Tsongas.

"You can't con the voters. If you want respect you have to give them your respect by telling them where you are and [not changing] your views with every season," McCain said.

McCain also touted his military background as making him more qualified for the Oval Office than his opponents.

"I've run the largest squadron in the U.S. Navy history, and I mean not run but led, controlled tens of millions of dollars of assets, trained young brave americans," McCain said. "I'll defend my leadership of thousands of men and women with the management of anyone else, and I'll say that it helps that I have a background in military and national security issues. I need no on the job training," he said.

Mike Huckabee shared McCain's sentiment that the Republican field is strong, but cited his approval among values voters as strong evidence of his conservative merits.

"Voters who consider themselves value voters, given the opportunity, overwhelmingly I win those contests," Huckabee said. "It's clear that this country and this part of our party want someone who's a hardworking conservative, not just saying it," Huckabee said.

Huckabee asserted his constancy of record as another solid point for his camp, which has seen progressive increases in support and poll numbers over the past few months. On a range of issues--abortion, gun control, gay marriage and tax cuts--Huckabee pointed out he has only ever had one position.

"Nobody's gonna find some YouTube moments of me saying anything other than what I am today," Huckabee said.

Asked whether he was the "true" conservative among his competitors, Huckabee said that was for the voters to decide.

"Be careful of candidates better at lip syncing than singing from the heart." Huckabee said. "I'm not gonna go out there and say I'm the only conservative in the race but I'm authentic," he said.

As the former governor of Arkansas, Huckabee said he had more executive experience than any of the candidates from either party.

Huckabee and McCain appeared on a special hour of FNS previewing the Republican debate in Orlando Sunday night, to be aired live on the FOX News Channel at 9 p.m.