Welcome to Ohio, springtime crossroads in the battle for control of the House, where the political parties, outside groups, attack advertising, surrogate campaigning and more are in full flower.

The two parties have spent more than $600,000 combined trying to influence the fate of Democratic write-in hopeful Charlie Wilson in one district, a highly unusual commitment that reflects the importance that Republicans and Democrats place on every potentially competitive seat.

MoveOn.org, a liberal group, has pummeled veteran Republican Rep. Deborah Pryce in her Columbus-area district, paying for television commercials so controversial that some stations declined to run them. Emily's List waded early into a Democratic primary battle to the north on behalf of Betty Sutton, part of its campaign to elect abortion rights advocates to Congress.

There's more.

First Lady Laura Bush is penciled in for a fundraiser next week for Pryce, and Sen. John McCain of Arizona, the potential 2008 presidential candidate, swung through this month to campaign in Cincinnati for Rep. Steve Chabot.

Across the state, scandal-scarred Republican Rep. Bob Ney is expected to survive a primary challenge on Tuesday, but some party strategists privately say they hope he will then step aside and allow them to field a replacement candidate with a better chance of holding the seat in the fall.

Overall, "I'd rather be us than them," says Rep. Rahm Emanuel of Illinois, the chairman of the Democratic Congressional Campaign Committee.

He made it clear the Democrats' road to a majority runs through Ohio. Asked whether the party must win seats in the state to capture the House, he said, "Yes, and we're going to. We have to and we will."

Rep. Tom Reynolds of New York, chairman of the GOP campaign committee, sized up the situation differently.

"Everybody told me that Ohio was doom and gloom and that Republicans were headed to extinction," he said. "I think that as we look at House seats we're going to hold our own. We won't take it for granted ... but we're certainly holding our own."

Solely in terms of political punch, Ohio arguably has more to lose from a Democratic takeover of the House than any other state.

Two Ohioans, newly elected Majority Leader John Boehner and Pryce, hold spots at the Republican leadership table. Two other members of the delegation, Reps. Ralph Regula and David Hobson, chair appropriations subcommittees. Regula oversees Congress' largest annual non-defense spending bill, covering health and education programs. Hobson has responsibilities for funding of energy and water projects.

Among the four, only Pryce faces significant opposition. But a Democratic takeover would strip the chairmen of their gavels and cost the GOP leaders their ability to set the House's legislative agenda in the last two years of President Bush's term.

Ohio also stands as a symbol of the national competition between Republicans, a dozen years in the majority, and Democrats, who need to gain 15 seats to take control.

Bush's statewide popularity has declined since Ohio voters sealed his re-election victory in 2004. Partially as a result, Democrats claim a chance to win seats that have been out of reach for years, the same argument they make on a national scale.

Republicans scour for opportunities district by district, rough going given Bush's diminished support. They nurse hopes of capturing a seat along Lake Erie that Rep. Sherrod Brown is giving up to run for Senate, but concede their chances hinge on the outcome of a crowded Democratic primary.

Judging by the involvement of the two political parties, the pre-primary combat is strongest in a district that stretches for 300 miles or more along the Ohio River as it forms the state's border with Kentucky, West Virginia and Pennsylvania.

Wilson, a state senator and the party favorite, failed to gather enough valid signatures to qualify for the ballot. The party establishment spurned other hopefuls and swung behind a write-in campaign.

Emanuel arranged for Democratic households to receive a recorded phone call from Bill Clinton. "Charlie has the most experience, best ideas, and he is supported by me .... and all 12 Democratic County Chairs," says the former president.

Eager to keep Wilson off the ballot, Republicans criticized him in television commercials that said millions of gallons of raw sewage had been secretly dumped into the Ohio River when he was chairman of the Eastern Ohio Regional Wastewater Authority.

Democrats leapt to his defense, saying opponents were against Wilson because he "fought the big oil and gas companies and won't 'yield' to President Bush and Republicans who are taking us the wrong way."

The campaign is more straightforward in the middle of the state, where Pryce has long been secure and drew 60 percent of the vote in 2004. But Democratic presidential candidate John Kerry lost narrowly to Bush in the district, which includes Ohio State University, and Democratic strategists have touted their chances for months.

Democratic challenger Mary Jo Kilroy, a county commissioner, calls Pryce a rubber stamp for the administration and hopes to tie her to the president as well as to corruption in Washington.

After seven terms, Pryce has told associates she recognizes she is in the toughest fight of her career. She is raising campaign funds aggressively, and her most recent federal report showed $1.5 million cash on hand.

Kilroy reported $355,000, a distinct disadvantage as she enters a general election campaign against a longtime incumbent. She hopes to recoup with the help of Emily's List, an organization that says it raised more than $10 million two years ago for fewer than 24 candidates in scattered races.

MoveOn is active, too, targeting Pryce as one of four Republican incumbents in its opening wave of attacks. "The goal of the program is to show that the House is up for grabs, and we believe we can do that by working in the districts that are not in the top tier," said Jennifer Lindenauer.

The initial effort ran into turbulence, though, when some stations rejected the ads.

It was yet another sign that the campaign has come early to Ohio.