WASHINGTON, DC - MAY 30:  Rudy Giuliani, former New York City mayor and current lawyer for U.S. President Donald Trump, speaks to members of the media during a White House Sports and Fitness Day at the South Lawn of the White House May 30, 2018 in Washington, DC. President Trump hosted the event to encourage children to participate in sports and make youth sports more accessible to economically disadvantaged students.  (Photo by Alex Wong/Getty Images)
Alex Wong/Getty Images
WASHINGTON, DC - MAY 30: Rudy Giuliani, former New York City mayor and current lawyer for U.S. President Donald Trump, speaks to members of the media during a White House Sports and Fitness Day at the South Lawn of the White House May 30, 2018 in Washington, DC. President Trump hosted the event to encourage children to participate in sports and make youth sports more accessible to economically disadvantaged students. (Photo by Alex Wong/Getty Images)
Now playing
02:15
Giuliani sought visa for Ukrainian promising dirt on Dems
US House Minority Leader, Kevin McCarthy, Republican of California, speaks during his weekly press briefing on Capitol Hill in Washington, DC, on March 18, 2021.
MANDEL NGAN/AFP/Getty Images
US House Minority Leader, Kevin McCarthy, Republican of California, speaks during his weekly press briefing on Capitol Hill in Washington, DC, on March 18, 2021.
Now playing
01:37
Hear what Republicans are saying about Kevin McCarthy's move
NEW YORK, NEW YORK - MARCH 08: New York Gov. Andrew Cuomo speaks at a vaccination site at the Jacob K. Javits Convention Center on March 8, 2021 in New York City. Cuomo has been called to resign from his position after allegations of sexual misconduct were brought against him. (Photo by Seth Wenig-Pool/Getty Images)
Seth WenigPool/Getty Images/
NEW YORK, NEW YORK - MARCH 08: New York Gov. Andrew Cuomo speaks at a vaccination site at the Jacob K. Javits Convention Center on March 8, 2021 in New York City. Cuomo has been called to resign from his position after allegations of sexual misconduct were brought against him. (Photo by Seth Wenig-Pool/Getty Images)
Now playing
02:29
New York Gov. Cuomo to receive over $5 million from book deal
CNN/Getty Images
Now playing
01:25
'Complete abdication': Borger slams McCarthy's announcement
Arizona Border Patrol Sciutto 1
USCBP
Arizona Border Patrol Sciutto 1
Now playing
06:18
Authorities face big challenges at Arizona border. Here's why
US President Joe Biden speaks about the March jobs report in the State Dining Room of the White House in Washington, DC, on April 2, 2021. - The US economy regained a massive 916,000 jobs in March, the biggest increase since August, with nearly a third of the increase in the hard-hit leisure and hospitality sector, the Labor Department reported on April 2, 2021.
MANDEL NGAN/AFP/Getty Images
US President Joe Biden speaks about the March jobs report in the State Dining Room of the White House in Washington, DC, on April 2, 2021. - The US economy regained a massive 916,000 jobs in March, the biggest increase since August, with nearly a third of the increase in the hard-hit leisure and hospitality sector, the Labor Department reported on April 2, 2021.
Now playing
03:11
US labor shortage working against Biden's economic goals
tom williams rep clyde resurfaced photo
tom williams rep clyde resurfaced photo
Now playing
04:04
Photo shows Rep. Clyde barricading door during insurrection
President Joe Biden speaks about distribution of COVID-19 vaccines, in the East Room of the White House, Monday, May 17, 2021, in Washington. (AP Photo/Evan Vucci)
Evan Vucci/AP
President Joe Biden speaks about distribution of COVID-19 vaccines, in the East Room of the White House, Monday, May 17, 2021, in Washington. (AP Photo/Evan Vucci)
Now playing
02:12
Biden announces US will share more vaccines globally
Now playing
03:48
Attorney for Gaetz ally issues ominous warning
Stephen Richer EBOF 05172021
CNN
Stephen Richer EBOF 05172021
Now playing
04:28
'Exasperated': GOP Arizona election official reacts to Trump's election lie
US Navy
Now playing
05:51
Retired US Navy Chief explains tech witnessed in UFO aircraft sighting
The U.S. Supreme Court on April 29, 2021 in Washington, DC.
Stefani Reynolds/Getty Images
The U.S. Supreme Court on April 29, 2021 in Washington, DC.
Now playing
02:20
Supreme Court to take up case next term that could limit Roe v. Wade
Getty Images
Now playing
00:50
Ex-federal prosecutor: This is 'potentially devastating' for Gaetz
Now playing
03:17
Avlon calls out ridiculousness of Arizona election audit
CNN
Now playing
02:26
GOP lawmaker rips colleagues' 'bogus' insurrection claims
US President Donald Trump boards Air Force One before departing Harlingen, Texas on January 12, 2021. (Photo by MANDEL NGAN / AFP) (Photo by MANDEL NGAN/AFP via Getty Images)
Mandel Ngan/AFP/Getty Images
US President Donald Trump boards Air Force One before departing Harlingen, Texas on January 12, 2021. (Photo by MANDEL NGAN / AFP) (Photo by MANDEL NGAN/AFP via Getty Images)
Now playing
04:41
Axios: Trump tried to pull troops from around world after election loss
(CNN) —  

New York federal prosecutors examining Rudy Giuliani’s Ukranian business dealings are mindful of both the approaching 2020 presidential election and of the difficulty of prosecuting foreign lobbying violations as they move forward in their investigation, according to people familiar with the matter.

These people say charges against President Donald Trump’s personal lawyer aren’t certain or imminent, but that Giuliani has come into prosecutors’ crosshairs as a central focus during the months-long inquiry.

In recent days, Giuliani has been in advanced discussions to hire Daniel L. Stein, a white-collar criminal defense attorney who is a veteran of the Manhattan US Attorney’s office, to represent him in the investigation, sources say.

Prosecutors are examining possible financial crimes connected to Giuliani’s Ukraine work, as well as possible foreign lobbying violations for those efforts. Giuliani is also the focus of a related counterintelligence inquiry.

The Giuliani investigation is part of a broader inquiry that includes some of his associates. That probe began as early as February, but prosecutors delayed certain investigative steps until recently in an effort to avoid alerting people implicated in the probe and prevent it from becoming public.

On October 9, however, informed that some targets in the case were planning to leave the country, officials arrested and charged several of Giuliani’s associates, including two who had introduced him to former and current Ukrainian officials as he searched for what he has said is damaging information connected to Trump’s political rival, Democratic presidential contender Joe Biden.

Those two, Igor Fruman and Lev Parnas, and two co-defendants were indicted for allegedly funneling foreign money into US elections. All have pleaded not guilty.

Having been forced to bring the case unexpectedly, prosecutors worked at the office late into the night on the day the associates were arrested, and since have issued subpoenas and conducted multiple property searches of people connected to the alleged scheme.

According to the indictment, part of the campaign-finance scheme was designed to encourage a US congressman to pursue the ouster of the US ambassador in Kiev, Marie Yovanovitch. After Giuliani and other Trump allies complained that she stood in the way of Giuliani’s investigative efforts in Ukraine, Trump removed her in May.

As prosecutors examine possible financial crimes connected to Giuliani’s Ukraine work, they could consider a range of charges. They are also weighing possible foreign lobbying violations for those efforts, but they are cautious about bringing such lobbying charges, especially without other accompanying charges. That’s in part because prosecutors in the Manhattan US Attorney’s office are wary about the viability of cases concerning violations of what’s known as the Foreign Agent Registrations Act after having observed how other recent cases have fared.

A spokesman for the US Attorney’s office declined to comment.

Late last year, the New York office declined to bring charges of unregistered foreign lobbying against the former White House counsel under President Barack Obama, Greg Craig, CNN has reported. That case was eventually prosecuted by the DC US Attorney’s office, and Craig was found not guilty in early September.

Prosecutors in New York monitored Craig’s trial closely, according to people familiar with the matter, and when he was acquitted they felt vindicated by their decision to drop the case.

Later in September, a federal judge overturned the conviction of an associate of former Trump national security adviser Michael Flynn on similar charges.

In Giuliani’s case, the investigation is still in its early stages and new information could inform their prosecutorial decisions.

In a pair of interviews with CNN last week, Giuliani said any work he did for foreign governments was only “for security purposes.”

“I’m seeing that I’m being investigated for lobbying. I haven’t done that. I see that I’m being investigated for representing a foreign government. I haven’t done that,” he said. “I’ve had a clause in my contracts since the Bush administration that I would not lobby or represent a foreign government.”

He criticized the Manhattan US Attorney’s Office, of which he was previously the head, saying it has acted improperly by failing to make him aware of its inquiry.

“Any neutral observer would say that if they’re investigating me and haven’t notified me, there is something wrong with that investigation. Not exactly a good faith investigation,” Giuliani said.

As they pursue Giuliani, prosecutors are acutely aware of the need to consider the election cycle and next year’s presidential contest.

In 2018, the year of the congressional midterm elections, the office charged two politically sensitive cases: one against Michael Cohen, Trump’s former personal attorney, and another against Chris Collins, then a Republican congressman who was up for reelection that year.

The office charged both in August, around two-and-a-half months prior to the midterms, after weighing both the need to bring charges in a timely fashion and to avoid taking unnecessary steps that could influence an election.

Cohen pleaded guilty that August and is serving a prison sentence. Collins, who won his reelection while under indictment, ultimately pleaded guilty earlier this year and resigned his seat.

CNN’s Dana Bash and Taylor Romine contributed to this report.