Bob Menendez's challenger Andy Kim's chances of winning New Jersey's senate elections, according to polls

As Bob Menendez's 18-year-long stint in the Senate approaches its end, following his bribery conviction in July, all eyes are set on the race to fill the New Jersey seat in the Upper House.

The front-runner to do so is Democratic lawmaker Andy Kim, who was initially Menendez's main contender in the Democratic primary but ended up as the party's representative as the incumbent lost support amid his trial.

Menendez filed to run as an independent before his conviction, but most polls showed him with single-digit levels of support, unable to make a clear run without the Democratic party behind him.

Menendez finally announced his resignation from the Senate following the conviction. It will take place on August 20. And even though he did not expressly say he won't take part in November's elections, his chances of regaining a seat are slim to none.

FiveThirtyEight's poll aggregator shows Kim with a solid lead over Republican candidate Curtis Bashaw. The latest surveys, which took place in late June, analyzed two scenarios: one with Menendez in contention and one without.

The former had 810 respondents and showed Menendez with only 3% of the support. Rep. Andy Kim was in the lead with 39% compared to Bashaw's 33%. Predictably, the scenario didn't change much without the current senator in the equation: Kim led with 41% while bashaw had 34%.

There has not bee much change in the candidates' levels of support over the past few months. A series of surveys by Fairleigh Dickinson University in early April also considered different scenarios, but Kim kept the lead in all of them.

Concretely, respondents were asked to choose between Bashaw and Christine Serrano Glassner, the Mandham Borough Mayor who made an unsuccessful senate run. They also included Menendez and a case without him. Kim's level of support oscillated between 44% and 48%, while the Republican failed to break 40%.

Kim could end up in the Senate even before, as he is being floated as a potential replacement of Menendez following his planned resignation. New Jersey Governor Phil Murphy will be able to select a "temporary appointment" to finish the senator's term and Kim could be the pick.

However, according to the New York Post grudges between him and Tammy Murphy, the governor's wife, could lead the governor to pass him over.