Also in the wings is U.S. Rep. C. A. Dutch Ruppersberger of Baltimore County, who has said he's considering a State House run. As the only significant potential candidate from the Baltimore area, Ruppersberger would be competing for white working-class votes that Gansler would need to overcome Brown's advantages. Many Democrats are skeptical that Ruppersberger would give up a safe House seat for an iffy campaign for governor.

Brown is expected to formally announce Ulman as his running mate at an event in Columbia this morning, the same day Harford County Executive David R. Craig is to launch his Republican campaign.

One of the highlights in Columbia is the expected announcement that U.S. Rep. Elijah E. Cummings is throwing his support to Brown and Ulman. The veteran Baltimore congressman is regarded as highly influential among Maryland Democrats, particularly African-American voters.

However the Democratic race shapes up, Gansler is faced with the challenge of finding a running mate who brings anything near to as much as Ulman can contribute to the Brown ticket. Not only does it lend geographic balance, but Ulman comes to the ticket with $2.1 million in his campaign kitty. The money can help Brown, who listed $1.6 million in his last report, close Gansler's considerable funding lead.

Gansler's aides concede that Ulman has strong qualifications but point to his campaign treasury as the main reason Brown chose him as a running mate.

"I'm not contesting his record in Howard County. What he really brings to the ticket is money," said Gansler media consultant Bill Knapp. "Beyond Howard County, Ulman is virtually unknown among Democratic primary voters."

Knapp dismissed the idea that the Brown-Ulman ticket can raise money or build support more effectively than Gansler can on his own. He said Brown is introducing his "dance partner" before he's even introduced himself to voters.

"For a campaign desperate to demonstrate that their candidate can stand on his own record, rushing out to name a running mate seems really odd," Knapp said.

Justin Schall, campaign manager for Brown, bristled at the suggestion that Ulman was brought on the ticket solely for his campaign war chest.

"That's insulting to the people of Howard County and to anyone who values the better schools, stronger economy and healthier lives that Ken Ulman has fought for as county executive," Schall said.

As an African-American, Brown enjoyed a flexibility to choose Ulman as a running mate that Gansler did not. Both the attorney general and the Howard executive are white males in a party that prides itself on diversity. The state hasn't elected a ticket of two white males since 1990.

"I would be shocked if any of the major candidates does not build meaningful diversity into their ticket," said Sen. Jamie Raskin, a Montgomery County Democrat who hasn't taken sides in the race.

Raskin said the decision of when to formally jump into the race may be mostly a matter of personal style.

"Some politicians like running a marathon and some politicians like to run a sprint. And you won't know which strategy is the shrewder one until the race is over," he said.

Today's campaign events

•Harford County Executive David Craig plans to formally announce his Republican candidacy for governor this morning in Havre de Grace.

•Lt. Gov. Anthony Brown, a Democratic candidate for governor, is expected to announce this morning in Columbia that Howard County Executive Ken Ulman will be his running mate.

•The Democratic and Republican primaries for governor are June 24, 2014. The general election is Nov. 4, 2014.