In a Democratic Senate primary race featuring two candidates aligned ideologically, the main concern for Democratic voters should be choosing the candidate who will make the stronger general election contender and be most effective if elected to the Senate.

We believe that candidate is Congressman Chris Murphy, now representing the state's 5th District.

Both Mr. Murphy and the candidate challenging him in the primary, former Secretary of the State Susan Bysiewicz, share many of the policy views espoused by this newspaper. Both will fight to retain and fully implement the Affordable Care Act and help fulfill its goal of assuring near universal health coverage for Americans. Both support the president's proposal to let the Bush tax cuts expire for couples making $250,000 and over, while retaining them for the middle class. And both would resist the attack from the political right on women's health and reproductive rights.

Neither, unfortunately, has a serious plan for the other side of the budget ledger - reducing spending. But Mr. Murphy, at least, says he is ready to look at ways to curb the growth of entitlement spending. Ms. Bysiewicz says only she will "protect" Medicare and Social Security, perhaps to the point they are bankrupt.

Mr. Murphy is the better politician. He is more affable, able to make his point in a debate or discussion without coming across as strident, quick to introduce personal anecdotes to make confusing, multifarious policy matters more understandable. These skills count in an election. And this Senate race to elect a successor to retiring Sen. Joe Lieberman could be a close one.

The next U.S. Senate could face major decisions from the very start. The post-election lame duck Congress will face the "fiscal cliff," when huge mandated cuts, including in defense, and the expiration of all the Bush tax cuts are set to take effect unless there is new legislation. It would be too much too soon, potentially tipping the nation into recession. Lame-duck lawmakers could well decide on a temporary fix that passes the problem to the incoming House and Senate. The decisions made could prove monumental.

With his experience as a congressman, and his willingness to work across the aisle - demonstrated by his co-chairing of the bipartisan Center Aisle Caucus - Mr. Murphy appears ready to be a player in that important process and assure Connecticut is not shortchanged in any budgetary deals.

Ms. Bysiewicz seems to us to be more a natural administrator than a legislator. On balance, she was a good secretary of the state.

But her effort in the last two years to move into a new political office, any office, suggests someone whose goal is to move up the political ladder however she can, rather than find the niche where her skills best match service to the public. In 2010 she abandoned her race for governor when a seemingly easier political prize emerged - attorney general - after Richard Blumenthal announced his successful run for the Senate. She was forced from that race, however, when the state Supreme Court ruled that as a non-practicing attorney she did not meet the statutory requirements for the office. It was an embarrassing exit. Now she wants to be a senator.

It was also troubling to see Ms. Bysiewicz, in an effort to defeat Mr. Murphy in this primary, allow her commercial attacking him to continue airing for weeks while acknowledging its primary claim - that Murphy is the top recipient of campaign contributions from hedge funds among all Democrats in Congress - was false. He is fourth on the list. Ms. Bysiewicz rationale for keeping the commerical on air was that the bogus accusation was close enough. No, it was wrong and should have been removed immediately or corrected.

In contrast, Mr. Murphy has taken the high road. During a recent debate the subject of the lack of ballots in Bridgeport during the 2008 election, on Bysiewicz's watch as secretary of the state, came up. Mr. Murphy could have attacked, but didn't, turning the topic instead to Republican efforts to reduce turnout through esoteric voter identification laws. Democrats should take notice.

The Day endorses Chris Murphy in the Aug. 14 Democratic primary.

The Day will make its endorsements for the general election in the fall.