The White House Wednesday showed it is ready to play an active role in choosing Democratic candidates this year, as President Barack Obama called Connecticut Attorney General Richard Blumenthal to offer his backing in the race to succeed retiring Sen. Chris Dodd (D).

Blumenthal jumped into the race Wednesday right after Dodd announced he will not seek re-election, and he is viewed as the favorite to win the Democratic primary in August.

Obama clearly wants Democrats unified behind Blumenthal. The move appeared designed to help get businessman Merrick Alpert out of the primary contest and ward off any other potential competitors for Blumenthal.

In a call to Blumenthal Wednesday evening, Obama congratulated him on his decision and offered to assist in the campaign, according to a White House source.

Amid strong Republican challenges for Democratic seats in other states, Democrats are especially keen to keep Dodd’s seat in their column.

Obama’s quick decision to phone Blumenthal shows that the president is ready to wade in aggressively in local races as Democrats seek to field the best team they can against what are expected to be strong GOP challenges.

The president’s backing of Blumenthal tracks his support for Sen. Arlen Specter (D-Pa.) in Specter’s tough primary fight for the Democratic nomination in his state. But Obama’s support for Specter is widely viewed as at least partially payback for Specter’s decision to switch parties last year.