DES MOINES, Iowa (AP) - An Iowa caucus campaign that has cycled through several Republican presidential front-runners entered its final week Monday, as unpredictable as the day conservatives began competing to emerge as Mitt Romney's chief rival.
Romney, the former Massachusetts governor, released a new television commercial for the state in which he cited a "moral imperative for America to stop spending more money than we take in. It's killing jobs," he said.
Texas Gov. Rick Perry countered with an advertisement that said four of his rivals combined - none of them Romney - have served 63 years in Congress, "leaving us with debt, earmarks and bailouts."
Former Pennsylvania Sen. Rick Santorum, who has invested more time in Iowa than any other contender, countered that "most Americans now believe that a little bit of experience going into a job like president is probably a good thing."
Santorum was the only presidential candidate in the state during the day.
That changes Tuesday, with bus tours planned by Perry, former House Speaker Newt Gingrich and Minnesota Rep. Michele Bachmann, all eager to energize their existing supporters and attract new ones.
Texas Rep. Ron Paul arrives Wednesday. Recent polls suggest he is peaking as caucus day approaches, a rise that has him tied with Romney or even ahead, and drawing more scrutiny for his views.
The result figures to be a short but intense stretch of campaigning through small towns and even smaller towns, the sort of one-on-one politicking that has largely vanished in the electronic age.
Failing that, it will pay tribute to the types of cuisine that prosper in early 21st century America.
The Perry bus will belly up to Doughy Joey's in Waterloo and to the Fainting Goat in Waverly, an establishment whose website says "After 10 p.m., we are the type of place your mothers warned you about." Perry also will visit a vineyard and winery in Carroll.
Bachmann will make an early-winter stop at a Dairy Queen, as well as Pizza Ranch establishments in Harlan, Red Oak and Atlantic, three localities with a combined population of 17,282.
It's not all about the food, though.
Perry has a stop arranged at the Glenn Miller Museum in Clarinda, population 5,301, where the great bandleader was born.
The Texas governor also has a distinction that none of his rivals can boast, a town that shares his name. Thus, Perry will visit Perry.
There were signs of strategic shifts as candidates struggled to stand out in advance of the straw poll next week that inaugurates the round of primaries and caucuses that will pick a nominee to oppose President Barack Obama next fall.
Perry's new ad shows images of Gingrich, Paul, Santorum and Bachmann as it criticizes Congress and renews the governor's call for halving lawmakers' pay and time spent in Washington.
Despite the commercial's implication, Gingrich and Santorum were out of Congress when the multibillion-dollar financial bailouts of 2008 occurred. Paul and Bachmann voted against the legislation.
Still, the approach taken suggests the Texas governor is more concerned with outpacing Paul, Bachmann, Santorum and Gingrich on caucus night that he is in defeating Romney.
The former Massachusetts governor, making his second try for the White House, has a well-funded and well-organized campaign nationally and in Iowa, as well as allies who are spending heavily on television advertisements through an independent organization known as a super PAC.
While others have periodically risen to challenge him, Romney has kept his support from seriously eroding in the polls, consistently remaining near the top.
A victory in Iowa does not necessarily translate into the Republican presidential nomination. Yet history suggests that contenders who finish farthest behind next week will quickly drop out, underscoring the significance of the struggle to emerge as Romney's chief rival.
The most recent presidential hopeful to surge and then falter is Gingrich. The former House speaker's campaign imploded last summer and still shows the after-effects: a shortage of funds to counter attack ads in Iowa, and failure to qualify for the primary in Virginia in March.
After insisting he would run a purely positive campaign, Gingrich let it be known he was about to attack Romney on one of his presumed areas of strength, his economic proposals.
R.C. Hammond, a spokesman for Gingrich, said the candidate would make the case that Romney has advanced "very timid ideas that will do little to get people back to work."
Gingrich favors an end to taxes on investment income and dividends, while Romney wants to end them only for individuals with incomes of $200,000 or less.
Gingrich also has proposed an optional 15 percent flat tax on income. Under the plan, taxpayers could stay in the current system, which has a top tax rate of 35 percent on taxable income above $379,150, or switch to the new flat rate, which would apply to income at all levels.
Romney favors retaining the current graduated income tax system, with lower rates than currently exist.
Gingrich is at least the fourth front-runner to falter since the campaign began in earnest in Iowa earlier this year.
Bachmann, who won a straw poll at the Iowa State Fair last summer, was briefly atop polls in the state. So, too Herman Cain, who subsequently suspended his campaign after a woman claimed she and Cain had a long-term extramarital affair.
Perry also soared to the top of the surveys when he entered the race last summer, then fell after a string of subpar debate performances.
Santorum has yet to experience the type of sudden surge that others in the race enjoyed but has doggedly campaigned in all 99 of the state's counties in hopes of rallying social conservatives to his side.
Associated Press writer Philip Elliott contributed to this report.