Democrats and Republicans will hold their state conventions in Des Moines tomorrow.

Democrats will gather in downtown Des Moines and Fred Hubbell — the party’s nominee for governor –will reveal who he’s chosen as a running mate.

“Of course, our focus as been on the primary. We had to win the primary before we had the opportunity to choose a lieutenant governor,” Hubbell said last Friday on Iowa Public Television, “and we will choose a very talented, capable person to be our lieutenant governor.”

Speculation has centered on a few names, including two women who are state senators. Since 1990, every Democrat and Republican nominated to run for governor has opted for “gender balance” at the top of the ticket. Hubbell said he’s had one major consideration.

“Pick a person who is very talented, very experienced,” Hubbell said on IPTV last Friday, “and, if something were to happen to me as governor, could step in and do a great job.”

Republicans are holding their state convention across town, on the state fairgrounds. The GOP delegates will formally nominate Adam Gregg as their party’s lieutenant governor candidate. Governor Kim Reynolds announced he’d be her running mate and governing partner in May of last year, the day after she took over from departing Governor Terry Branstad.

An amendment to Iowa’s Constitution changed the process of electing lieutenant governors in 1990. Below is the list of Democrats and Republicans who’ve run together as a team since then.

1990:

Republican gubernatorial nominee Terry Branstad, the incumbent and eventual winner in 1990, chose state Senator Joy Corning of Cedar Falls, as his running mate. This was the first election in which the new state constitutional amendment took effect, so candidates for governor and lieutenant governor in Iowa ran as a team — just as the president and vice president do.

Democratic gubernatorial candidate Don Avenson chose Jo Ann Zimmerman as his running mate. Zimmerman, the first woman elected as lieutenant governor, was also the state’s last independently elected lieutenant governor. Zimmerman, a nurse from Waukee, ended her campaign for governor before the primary and became half of the “A to Z” ticket.

1994:

Republican Terry Branstad successfully ran for a fourth term as governor and Joy Corning was again his running mate.

Democratic gubernatorial candidate Bonnie Campbell chose Leonard Boswell, a military veteran and state senator from Davis City, as her running mate. Boswell ran for congress in 1996 and served in the U.S. House until  January of 2013.

1998:

Democratic gubernatorial nominee Tom Vilsack and the winner of the 1998 election chose Sally Pederson as his running mate. Pederson, a Vinton native, was the former food editor of Better Homes and Gardens magazine, a former Meredith Corporation executive and she was active in civic organizations in the Des Moines area. Pederson later served as chairwoman of the Iowa Democratic Party.

Republican gubernatorial nominee Jim Ross Lightfoot chose Almo Hawkins of Des Moines as his running mate and she became the first African American nominated by a major party for statewide office when delegates at the 1998 state convention ratified Lightfoot’s choice. Hawkins, a former reporter for KCCI television in Des Moines, had worked in state government.

2002:

Democrat Tom Vilsack successfully ran for reelection and Sally Pederson was again his lieutenant governor running mate.

Republican gubernatorial candidate Doug Gross chose Debi Durham of Sioux City as his running mate. Durham was the head of the Siouxland Chamber of Commerce. She is currently head of the Iowa Economic Development Authority, a position she’s held since January of 2011.

2006:

Democratic gubernatorial nominee Chet Culver and the winner of the 2006 election chose Patty Judge as his running mate. Judge, a former state senator from Albia who had served two terms as Iowa’s first female secretary of agriculture, ended her own campaign for governor before the primary to become Culver’s running mate.

Republican gubernatorial nominee Jim Nussle chose Bob Vander Plaats as his running mate. Vander Plaats had run unsuccessfully for governor in 2002 and was running again in 2006, but ended his own campaign to become Nussle’s lieutenant governor running mate. (Vander Plaats ran a third time for governor in 2010, losing to Terry Branstad. See more below.) Vander Plaats is now president and CEO of The Family Leader.

2010:

Republican Terry Branstad successfully ran for a fifth term as governor, selecting state Senator Kim Reynolds of Osceola as his running mate. Reynolds had competition for the slot on the ticket at the GOP’s state convention that year, though. Bob Vander Plaats, who finished second to Branstad in the primary, was nominated at the convention by state Representative Dwayne Alons of Hull to be Branstad’s running mate. Congressman Steve King nominated Reynolds. Reynolds won the most votes from delegates, securing the lieutenant governor slot on the GOP’s 2010 ticket.

Democratic Governor Chet Culver and Lieutenant Governor Patty Judge sought reelection in 2010.

2014:

Republican Terry Branstad won a sixth term as governor with Kim Reynolds as his lieutenant governor running mate.

Democratic gubernatorial candidate Jack Hatch chose Cedar Rapids City Councilwoman Monica Vernon as his running mate. Vernon had just finished second in the Democratic Party’s primary in the first congressional district. Hatch announced Vernon as his pick a few days after the primary, before the state convention, at a union hall in Cedar Rapids.