WASHINGTON, June 16 (Reuters) - Georgia Republicans go to the polls Tuesday to select their candidate for U.S. Senate to take on incumbent Jon Ossoff, a rising Democratic star and potential presidential candidate in 2028.

Over the weekend, President Donald Trump endorsed U.S. Representative Mike Collins - and dubbing him "MAGA Mike" on Truth Social - over former football coach Derek Dooley in the state's primary runoff.

Outgoing Georgia Governor Brian Kemp, who angered the president by refusing to help him overturn the 2020 election result in Georgia, endorsed Dooley.

Voters in Alabama, Oklahoma and Washington, D.C., will also head to the polls, and Bay Area voters will winnow a crowded field of candidates hoping to serve out former U.S. Representative Eric Swalwell's term.

Here is what we're watching:

FACING THE OSSOFF FUNDRAISING JUGGERNAUT

Ossoff awaits the winner of a runoff between Collins and Dooley. Trump endorsed Collins over the weekend, calling him a "WARRIOR and WINNER" who supported Trump "from the very beginning."

"I don't know Derek Dooley, and neither does anyone else, but he seems like a nice person," Trump wrote on Truth Social.

"Unfortunately, he has lived outside of Georgia for most of his life, didn't vote in 2020 or 2016, and said that I lost Georgia in 2020 when, in actuality, the facts have now proven that I won by a lot!" Trump lost Georgia to Democrat Joe Biden in 2020 by 0.3 percentage points.

In response to the president's endorsement of Collins, Dooley said he has "great respect" for Trump but cast himself as the outsider best positioned to beat Ossoff, according to media reports.

Either Republican will struggle to compete with Ossoff's war chest, now flush with nearly $33 million compared to Collins' $1.2 million and Dooley's $1.7 million. Ossoff's team has said his campaign is powered by hundreds of thousands of small donors, with average donations each quarter ranging from $32 to $38. 

Georgia and Michigan are the only Trump-won states Senate Democrats are defending in November's midterm elections. Democrats would need to net four seats to win control of the chamber.

TRUMP'S CLOUT IN THE SOUTH

Trump will be looking to keep his streak alive on Tuesday after victories by candidates he endorsed in recent primaries.

In other runoffs on Tuesday, Trump endorsed Georgia Lieutenant Governor Burt Jones' gubernatorial bid. In Alabama, Trump has endorsed Representative Barry Moore's Senate campaign over former Navy SEAL Jared Hudson.

Jones faces businessman Rick Jackson in the race to succeed Kemp. The winner will run against Democrat Keisha Lance Bottoms, a former Atlanta mayor and past adviser to Biden.

While Trump may be picking winners in the primaries, the question remains whether his candidates can win in the general election in November, particularly when Trump himself isn't on the ballot.

"This is not going to be a particularly good year to be a Republican in this state," said Charles Bullock, a political science professor at the University of Georgia. "Democrats could win the governorship."

DC CONSIDERS A DEMOCRATIC SOCIALIST

With the departures of Mayor Muriel Bowser and congressional delegate Eleanor Holmes Norton, Washington will elect a new mayor for the first time since 2014 and a new non-voting delegate for the first time since 1990. 

Leading in the polls for mayor is Councilmember Janeese Lewis George, a democratic socialist in the mold of New York Mayor Zohran Mamdani.

Last week, Trump said he "wouldn't like it" if Lewis George were elected mayor and threatened to "take back Washington and run it on the federal basis" if she wins.

Her top opponent in the crowded race is former Councilmember Kenyan McDuffie. The two have spent nearly $6 million combined.

The top candidates to succeed Norton, 89, are Councilmembers Brooke Pinto and Robert White, and former Democratic National Committee deputy finance chair Kinney Zalesne. 

The primary winners in both races are expected to win the general election in the heavily Democratic district.

STATE VOTES ON MINIMUM WAGE

Oklahoma voters will choose whether to approve a ballot measure that would raise the state's $7.25 minimum wage to $15 by 2029. Republican Governor Kevin Stitt and more than 100 Republican state legislators oppose the increase, with lawmakers saying its passage would lead to "severe" economic fallout, such as job losses and rising prices.

But not all Oklahoma Republicans agree: Republican Labor Commissioner Leslie Osborn supports the ballot measure, telling a local news outlet everyday costs have risen while Oklahoma's minimum wage hasn't changed since 2009.

"You absolutely cannot pay the gas to get to a job, have an apartment and live extremely frugally. You're going to have to rely on government programs," she said. "As a Republican, we should want people ... to stand on their own two feet." 

THE RACE TO SUCCEED SWALWELL

On Tuesday, voters in the San Francisco area will hold an initial election to choose candidates to complete the term of Democratic Representative Eric Swalwell, who earlier this year ended his campaign for California governor and resigned from Congress amid sexual misconduct allegations. Swalwell denied the allegations.

Among the 11 candidates are State Senator Aisha Wahab and Bay Area Rapid Transit Board President Melissa Hernandez, both Democrats. The top two finishers, regardless of party, will advance to an August 18 special general election to serve through early January.

Wahab and Hernandez have already advanced to the November general election for a new full two-year term in the Bay Area district.