From KELOland.. (They said it, not me):

The two candidates who finished third and fourth in the Sioux Falls primary election for mayor asked their supporters to vote for Jamie Smith in the June 23 run-off election.
and..
Smith is a Democrat and a state Senator in South Dakota. He also ran for Governor as a Democrat. The third place finisher was former Republican State Rep. Greg Jamison.
With his endorsement of the standard bearer for the Walz/Biden Democrats in the state, I think the emphasis for Greg is on “former Republican.”

It would have been easier for Jamison to stay silent. He knew he would be criticized.
This was historically a non-partisan race and perhaps it should be again. I admire those who stand up for their beliefs even when the party tells them they shouldn’t. I think it takes courage.
And… agree with him or not… Jamie Smith seems to be a genuinely decent guy.
I’m looking forward to a change in the tone, tenor and tyranny of one party rule. A few in the ruling party realize that it has been hijacked by the most ardent followers of the sociopathic sexual predator in the White House – which includes the top vote getter in the governor primary. The inmates have been running the asylum, and some R’s have apparently had enough.
And who on God’s green earth can blame them?
As Elk says, this is a non-partisan race, as it should be. Potholes are not Democratic or Republican. And this blog is saying it is to stop a woman. No. It’s municipal politics. Nothing more, nothing less. Gender has nothing to do with it. She can also reach out to the other losing candidates for their support too. It’s good to see people reaching across party lines. America needs more of that, from both sides.
She did reach out to Jamison for an endorsement and did not get it. Jamison and Smith have been friends/friendly for years, so it’s not too surprising and if their spots been flipped in the polls we’d be talking about Smith endorsing Jamison.
That big donation she got has some people looking at her in a different way. After sixteen years of presumed infallability with every utterance made by the mayor’s office, she is starting looking like the business as usual candidate. Smith, by default, is the change candidate. It will all come down to the Gipper’s “Are you better off now then you were four years ago?” to decide which wya to go.
And don’t forget she did get a psuedo-endorsement a couple months back when she convinced Marshall Selberg to drop out of the race. He was at many of her fundraiser events during the last month or so of the campaign.
Most likely it results from their time in the senate when Smith impressed him with his willingness to work with republicans. Likely believed that this would be good for the city also.