The race to fill the Senate seat Sen. Joe Lieberman is vacating will be among the most important in the nation and certainly one of the most engaging. Republican Linda McMahon and Democrat Chris Murphy begin the general election as impressive candidates, both having easily dispatched their challengers in Tuesday's primaries.

Republicans have a great chance at taking control of the U.S. Senate. The GOP needs to pick up four seats to rule the Senate (just three if Mitt Romney is elected president and the vice presidential Senate tiebreaker is Republican Paul Ryan). Republicans are defending only 10 Senate seats, while Democrats must defend 23.

In making their decision in this race, voters should consider not only who may be the better senator but also who they want controlling the Senate. With the House likely to maintain a Republican majority, Senate control will be critical, regardless of the presidential outcome. If President Obama wins re-election it would mean his dealing with a Congress in which the opposing party controls both chambers. The result would be either progress through compromise or several more years of deadlock.

Conversely, if Mr. Romney becomes president it places Republicans in full control. Because of Senate rules, the GOP could make major changes to the tax code, budget, Medicare and Medicaid through the reconciliation process with even a single-vote majority. With the stakes that high, Mr. Murphy should expect some outside funding help from Democratic advocacy groups to counter, at least in part, Ms. McMahon's professional wrestling fortune.

The result is that Connecticut residents should hunker down for a barrage of political advertisements, many of them nasty and negative, in this Senate race. Fortunately, it appears there will also be opportunities to debate matters of substance.

The candidates exchanged press releases Wednesday, Mr. Murphy proposing a debate with Ms. McMahon on the issue of jobs and the Republican responded that she is prepared for up to four debates over the next three months, two of them on job creation. The Day has offered to host one of those debates locally in conjunction with WTNH-TV.

The seeming readiness to go head-to-head with her challenger appears to signal a shift in tactics for Ms. McMahon, who limited her exposure during the primary, participating in only a couple of debates and passing on editorial board meetings. Perhaps she saw no advantage in giving a primary opponent she was well ahead of and badly outspending, former Congressman Chris Shays, any additional exposure or in exposing herself to the barbs of editorial writers. In any event, if this is an indication of a change, it is welcomed.

Both candidates appear confident they can frame the debate to their advantage. Someone will be right. There are big differences.

Mr. Murphy wants to implement the Affordable Care Act, Ms. McMahon wants to repeal it. Ms. McMahon proposes to further cut taxes, while Mr. Murphy wants to let the Bush tax cuts expire for the wealthy and calls his proponent's tax plans unrealistic budget busters. Ms. McMahon will try to characterize her opponent as a career politician who is part of the problem, while he in turn will point to her legislative inexperience and challenge her policy proposals as paper thin.

This should be good.