If you are actually training for 26.2 miles, I would stop pretending the running is a side project.
It is the main event for a while.
That does not mean stop lifting.
I would keep lifting.
I just would not make the gym compete with the race build for every last bit of recovery.
I would keep strength and get rid of junk first
This is where a lot of lifters go too far in either direction.
Option one: keep the exact same lifting program while mileage climbs every week.
Option two: stop touching anything heavier than a grocery bag until race day.
I do not like either one.
Keep meaningful squat, hinge, press, pull, and single-leg work.
Then look at the extra sets that mostly exist because you had time and recovery for them before marathon training started.
That is where I would cut first.
Three good hard sets beat six mediocre sets when Sunday's long run is becoming its own event.
The long run gets protected
I would not put the hardest lower-body session right before the most important long run of the week and then call the schedule unlucky.
That was a choice.
If Sunday is the long run, Friday lower body may need to be lighter, shorter, or moved.
Saturday definitely does not need to become surprise leg day.
The same goes for hard running sessions.
Intervals, threshold work, and long runs are the expensive pieces.
Heavy lower-body lifting is expensive too.
Do not stack all of the expensive stuff into three days because the calendar looked convenient.
Mileage has to grow slower than motivation
This gets harder once a lifter discovers they actually enjoy running.
The lungs start feeling good.
Five miles is not intimidating anymore.
So eight sounds reasonable.
Then ten.
Your connective tissue did not necessarily sign that agreement.
I would rather have a boring mileage build that leaves the athlete healthy enough to keep training than a heroic three-week stretch followed by a month of trying to calm down a foot or shin.
Your lower-body lifting will probably feel different
This is normal.
A squat load that felt routine when you were running 12 miles a week may feel less routine when you are running 35.
That does not automatically mean strength vanished.
You are carrying more fatigue.
Use RIR.
Keep the effort where it belongs.
If today's planned weight turns into an ugly grinder way too early, adjust it and finish the useful work.
The goal during the heart of a marathon build may be maintaining strength, not proving every Monday that you still own the same gym numbers.
Fuel the running you asked your body to do
Longer mileage changes the food problem too.
If bodyweight is dropping faster than planned, long runs are getting worse, and the gym feels flat, I am going to look pretty hard at calories and carbohydrate before deciding the athlete suddenly became bad at training.
You cannot keep adding miles forever while pretending food needs stay exactly where they were during a lifting-only block.
The Macros for Hybrid Athletes guide covers that side.
The taper is not the time to panic-lift
Race day gets close.
Running volume comes down.
Suddenly you feel good.
This is where the lifter brain says, "Perfect time to see where my squat is."
I would leave that alone.
The point of the taper is showing up with fatigue coming down and fitness still there.
You do not need to manufacture a new recovery problem because the bar finally feels light again.
After the race, lifting can take the wheel again
This is the part I like about thinking in phases.
Running can be the priority without owning the whole year.
Finish the race block.
Recover.
Then bring lifting volume and strength emphasis back up while mileage comes down to something easier to maintain.
You are allowed to care about different things at different times.
That is a lot more realistic than trying to peak a marathon and a squat PR on the same Saturday.
If you are earlier in the process, use Running for Lifters. For weekly sequencing examples, see Hybrid Athlete Training.